CHAPTER 1 Introduction to Software Engineering

When people think about computers, the first thing that comes to their minds are the physical machines- monitor, keyboard, mouse and CPU. However, the software is the one that makes them useful. A computer software includes a set of programs that execute within a computer of any size and architecture, and data that are being processed by the programs and presented to users as hard or soft copies. It is built by software engineers through the employment of a software process that yields high quality work products that meet the needs of people who will be using the system. Nowadays, software is a very important technology of our lives because it affects nearly every aspects of it, including government, commerce, and culture. In this chapter, we will be discussing software engineering as a discipline in building quality computer software. A layered view will be used to outline the concepts needed to understand software engineering. Then, an understanding on the people involved in the software development effort will be discussed. It will be followed by the need for documentation and how to organize and document software engineering work products.

Software Engineering- A Layered View
Software Engineering is a discipline that applies principles of engineering to the development of quality software in a timely and cost-effective manner. It uses an approach that is systematic and methodological to produce quantifiable results. It makes use of measurement and metrics to assess quality, not only of the software but also the software process. They are also used to assess and manage the software development project. Software Engineering is viewed differently by different practitioners. Pressman suggests to view software engineering as a layered technology 1. This view consists of four layers, namely, quality focus, process, methods and tools. Figure 1.1 illustrates this software engineering view.

Tools Methods Process Quality Focus

Software Engineering – A Layered View

Quality Focus At the very foundation of this layer is a total focus on quality. It is a culture where commitment to continuous improvement on the software development process is fostered. This culture enables the development of more effective approaches to software engineering. Process The process integrates the other layers together. It defines a framework that consists of key process areas that define and enable rational and timely delivery of the computer software. The key process areas are the basis for the software project management. They establish what technical methods are applied, what tools are used, 1

what work products need to be produced, and what milestones are defined. They also include assurance that quality is maintained, and that change is properly controlled and managed. Method Methods define a systematic and orderly procedures of building software. They provide an overall framework within which activities of the software engineer are performed. These activities include a wide array of tasks such as requirements analysis, design, program construction, testing and maintenance. Methodology is the science of systematic thinking using the methods or procedures used in a particular discipline. There are several software engineering methodologies that are used today. Some of them are briefly enumerated below. Structured Methodologies: • Information Engineering • Software Development Life Cycle/Project Life Cycle • Rapid Application Development Methodology • Joint Application Development Methodology • CASE*Method Object-oriented Methodologies: • Booch Method The Booch method encompasses both a “micro development process” and a “macro development process”. The micro level defines a set of analysis tasks that are reapplied for each step in the macro process. Hence, an evolutionary approach is maintained. Booch’s micro development process identifies classes and objects and the semantics of classes and objects and defines relationships among classes and objects and conducts a series of refinements to elaborate the analysis model. • Coad and Yourdon Method The Coad and Yourdon method is often viewed as one of the easiest mthods to learn. Modeling notation is relatively simple guidelines for developing the analysis model are straightforward. A brief outline of Coad and Yourdon’s process follows: - Identify objects using “what to look for” criteria - Define a generalization/specification structure - Define a whole/part structure - Identify subjects (representations of subsystem components) - Define attributes - Define services • Jacobson Method Also called OOSE(object-oriented software engineering), the Jacobson method is a simplified version of the proprietary objectory method, also developed by Jacobson. This method is differentiated from others by heavy emphasis on the use-case – a description or scenario that depicts how the user interacts with the product or system. • Rumbaugh Method Rumbaugh and his colleagues developed the object modeling technique (OMT) for analysis, system design, and object-level design. The analysis activity creates three models: the object model (a

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representation of objects, classes, hierarchies, and relationships), the dynamic model (a representation of object and system behavior), and the functional model (a high-level DFD-like representation of information flow through the system). • Wirfs-Brock Method Wirfs-Brock, Wilkerson, and Weiner do not make a clear distinction between analysis and design tasks. Rather a continuous process that begins with the assessment of a customer specification and ends with design is proposed. A brief outline of Wirfs-Brock et al.’s analysis-related tasks follows: - Evaluate the customer specification - Extract candidate classes from the specification via grammatical parsing - Group classes in an attempt to identify superclasses - Define responsibilities for each class - Assign responsibilities to each class - Identify relationships between classes - Define collaboration between classes based on responsibilities - Build hierarchical representations of classes - Construct a collaboration graph for the system Tools Tools provide support to the process and methods. Computer-aided software engineering provides a system of support to the software development project where information created by one tool can be used by another. They may be automated or semiautomated. Most tools are used to develop models. Models are patterns of something to made or they are simplification of things. There are two models that are generally developed by system model is an inexpensive representation of a complex system that one needs to study while a software model is a blueprint of the software that needs to be built. Like methodologies, several modeling tools are used to represent systems and software. Some of them are briefly enumerated below. Structured Approach Modeling Tools: • Entity-relationship Diagrams • Data Flow Diagrams • Structured English or Pseudocodes • Flow Charts. Object-oriented Approach Modeling Tools: • Unified Modeling Language (UML)

Quality within the Development Effort
As was mentioned in the previous section, quality is the mindset that must influence every software engineer. Focusing on quality in all software engineering activities reduces costs and improves time-to-market by minimizing rework. In order to do this, a software engineer must explicitly define what software quality is, have a set of activities that will ensure that every software engineering work product exhibits high quality, do quality control and assurance activities, and use metrics to develop strategies for improving the software product and process.

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It is relative to the person analyzing quality. the quality of the software suffers. How do we define quality? Three perspectives are used in understanding quality. and coding normally done prior to the shipment of the products to the endusers. Common process guidelines are briefly examined below. For the ones developing and maintaining the software. Examples of which includes errors or faults found during requirements analysis. If the software does not add value to the business. They normally assess and categorized quality based on external characteristics such as number of failures per type of failure. when they want it. they take a look at the internal characteristics rather than the external. • Software Process Improvement and Capability Determination (SPICE). specifically. all the time. Failures are categorized as minor. They also judge it based on ease of use and ease in learning to use it. As software engineers. Quality of the Process There are many tasks that affects the quality of the software. These characteristics or attributes must be measurable so that they can be compared to known standards. quality of the process. Process guidelines suggests that by improving the software development process. The intent of the standard is to assist organization in developing an objective evaluation of the efficacy of any defined software process. we also improve the quality of the resulting product. It is also important to measure the value of the software in terms of business terminologies such as "how many sales orders were processed today?".e. It is a generic standard that applies to any organization that wants to improve the overall quality of the products. we value the quality of the software development process.What is quality? Quality is the total characteristic of an entity to satisfy stated and implied needs. Quality of the Product Quality of the product would mean different things to different people. systems or services that it provides. major and catastrophic. we build models based on how the user's external requirements relate to the developer's internal requirements. why do we need it in the first place?
How do we address the Quality Issues?
We can address quality issues by: 4
. i. quality in the context of the business environment. technical value of the software translates to business value. Improving the technical quality of the business process adds value to the business. Sometimes.. dollar value on return on investments (ROI) etc. Quality in the Context of the Business Environment In this perspective. It was formulated by the Software Engineering Institute (SEI). It is a standard that defines a set of requirements for software process assessment. • Capability Maturity Model Integration(CMMI). quality is viewed in terms of the products and services being provided by the business in which the software is used. As software engineers. the software has quality if it gives what they want. when a task fails. designing. For end-users. • ISO 9000:2000 for Software. It is a process meta-model that is based on a set of system and software engineering capabilities that must exists within an organization as the organization reaches different level of capability and maturity of its development process. we look at the quality of the product.

explicitly documented development standards (quality standards). one takes a look at specific characteristics that the software exhibits. Understand people involved in the development process including end-users and stakeholders. people are unduly optimistic in their plans and forecasts. It is characterized by the ease of upgrading and maintaining. Quality standards are sets of principles. Standards define a set of development criteria that guide the manner by which the software is engineered. Understand the systematic biases in human nature such as people tend to be risk averse when there is a potential loss. and implicit characteristics (developer's internal characteristics) that are expected of all professionally developed software. Manage user requirements because it will change over time. 5
. and guidelines to bring about quality in the process such as CMMI. Use Quality Standards.
Software Quality Assurance and Techniques
Software quality assurance is a subset of software engineering that ensures that all deliverables and work products are meet. formal technical reviews. It encompasses a quality management approach. Software Requirements are the foundation from which quality is measured. and people prefer to use intuitive judgment rather than quantitative models. secure and safe. control of software documentation and the changes made to it. effective software engineering technology (methods and tools). a multi-tiered testing strategy. It is considered as one of the most important activity that is applied throughout the software development process. It is the capability of the software to execute in different platforms and architecture. Software Quality A software has quality if it is fit for use. 2. a procedure to assure compliance with software development standards.. In order for it to work properly.e. • Reusability. 1. Its goal is to detect defects before the software is delivered as a final product to the end-users.1. 3. • Portability. It is the ability of the software to evolve and adapt to changes over time. Three important points should be raised from the definition of software quality. they influence the way software is developed such as good maintainability. and they comply with user requirements and standards. 4. 5. It is necessary to explicitly specify and prioritize them. Implicit characteristics must be identified and documented. methodologies. Requirements are the basis defining the characteristics of quality software. • Dependability. Characteristics of a Well-engineered Software To define a well-engineered software. This fosters an environment of collaboration and effective communication. 3. i. Commit to quality. Some of them are enumerated below: • Usability. It is the characteristic of the software that exhibits ease with which the user communicates with the system. It is the ability of the software to transfer from one system to another. procedures. it should conform to explicitly stated functional and performance requirements (user's external characteristics). 2. ISO 9000:2000 for Software and SPICE. and measuring and reporting mechanism. A mindset focus on quality is needed to discover errors and defects so that they can be addressed immediately. it is working properly. It is the characteristic of the software to be reliable. • Maintainability.

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. • audits and reviews to be performed. • procedures for error reporting and tracking. and • amount of feedback required. They identify the: • evaluation to be performed. Software Quality Assurance Activities Software Quality Assurance is composed of a variety of activities with the aim of building quality software. They document it and ensures that corrections have been made. 3. The SQA team participates in the development of the project's software process description. Formal Technical Reviews Work products are outputs that are expected as a result of performing tasks in the software process. to make projects more manageable. The development team selects a software development process and the SQA team checks it if it conform to the organizational policy and quality standards. • standards that are applicable. The SQA team prepares the SQA Plan. to ensure that the software has been represented according to defined standards. 2. 2. overseeing. The SQA team has responsibility over the quality assurance planning. they should be measurable and checked against requirements and standards. It involves two groups of people.• Efficiency. 5. They monitor and track defects or faults found with each work products. They document it and ensure that corrections have been made. 4. logic or implementation for any representation of the software. to achieve software that is developed in a uniform manner. 3. to verify that the software under review meets user requirements. The changes to this work products are significant. It is the capability of the software to use resources efficiently. They do this during the project planning phase. its goals are: 1. The SQA team reviews work products to check for compliance with defined standards. analyzing and reporting defects and rework. Specifically. A technique to check the quality of the work products is the formal technical review. Therefore. 4. These results contribute to the development of quality software. Activities involved are the following: 1. The SQA team ensures that deviations in the software activities and work products are handled based on defined standard operating procedures. The SQA team reports deviations and non-compliance to standards to the senior management or stakeholders. they should be monitored and controlled. They monitor and track deviations from the software development process. It serves to discover errors and defects that can be removed before software is shipped to the end-users.development team and SQA team. The SQA team reviews software engineering activities employed by the development teams to check for compliance with the software development process. Formal Technical Reviews (FTR) are performed at various points of the software development process. records keeping. and 5. to uncover errors in function. 6. • documents to be produced.

• Keep the number of participants to a minimum and insist on preparing for the review. and set another meeting for their resolutions. • Provide a checklist for the work product that is likely to be reviewed. • Statistics on types of errors are key. Originally. Conducting inspections require a lot of activities. It should aid in clarifying defects and actions to be done. However. • Review the work product NOT the developer of the work product. Materials are inspected at a particular rate which has been found to give maximum error-finding ability. specifications or function errors. • Inspections are carried out in a prescribed list of activities. Remind everybody that it is not time to resolve these issues rather have them documented. Reviews should not last more than two hours.A general guideline of conducting formal technical reviews is listed below. Fagan's Inspection Method It was introduced by Fagan in 1976 at IBM. Two formal technical reviews of work products used in industry are the Fagan's Inspection Method and Walkthroughs. It is managed by a moderator who as responsibility of overseeing the review. • Inspections are led by a trained moderator. model elements. • Minimize debate and rebuttal. Those rules are listed as follows: • Inspections are carried out at a number of points in the process of project planning and systems development. • Point out problem areas but do not try to solve them. data and code design etc. and used for reports which are analyzed in a manner similar to financial analysis. • inspectors are assigned specific roles to increase effectiveness. The goal of the review is to discover errors and defect to improve the quality of the software. The tone of the review should be loose but constructive. • Inspection are carried out by colleagues at all levels of seniority except the big boss. However. It also helps the reviewers stay focus. Preparation prevents drifts in a meeting. • Schedule the reviews as part of the software process and ensure that resources are provided for each reviewer. it is not time for problem-solving session. it can be extended to include other work products such as technical documents. It would required a team of inspectors assigned to play roles that checks the work product against a prepared list of concerns. It also helps the reviewers stay focus on the review. Writing down comments and remarks by the reviewers is a good technique. It follows certain procedural rules that each member should adhere to. Mention and clarify problem areas. • Inspection meetings are limited to two hours. It should be done and schedule for another meeting. They are categorized as follows: 7
. It checks the effectiveness of the review process. it was used to check codes of programs. It is inevitable that issues arise and people may not agree with its impact. Checklists of questionnaires to be asked by the inspectors are used to define the task to stimulate increased defect finding. A checklist provides structure when conducting the review. It is a good practice to write down notes so that wording and priorities can be assessed by other reviewers. It is more formal than a walkthrough. • De-brief the review. • Write down notes. • All classes of defects in documentation and work product are inspected not merely logic. • Plan for the agenda and stick to it.

An action list is a list of actions that must be done in order to improve the quality of the work product which includes the rework for the defects. Normally. Unlike the inspection where one has a moderator. • Reworking of the work product. • Following up the rework. They are listed below: • No manager should be present. Each inspector is given 1 to 2 hours alone to inspect the work product. • He distributes the necessary materials of the work product to the reviewers. He decides who will be the inspectors. Walkthrough A walkthrough is less formal than the inspection. This is optionally held where inspectors are given a chance to express their personal view on errors and improvements. moderator and the developer of the work product. • Walkthrough Proper
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. The moderator ensures that the defects on the work products are addressed and reworked. • Always document the action list. normally around 3 people. • Holding the meeting. the roles that they have to play. • Giving of the overview. He is discouraged to fix the defects or criticize the developer of the work product. where comments of their correctness are elicited. • Preparing. No discussion about whether the defect is real or not is allowed. • Criticize the product. A scribe is also present to produce an action list. These are later on inspected by other inspections. Emphasis is given to the way the inspection was done. moderates the walkthrough.• Planning. A defect list is produced by the moderator. not the person. a day or two in advance. would require many activities. similar with inspection. It can be omitted if everybody is familiar with the overall project. • He specifically asks each reviewer to bring to the walkthrough two positive comments and one negative comment about the work product. this is the developer of the work product. A moderator is tasked to prepare a plan for the inspection. Conducting a walkthrough. Some guidelines must be followed in order to have a successful walkthrough. The participants of the meeting are the inspectors. A 30-minute presentation of the project for the inspectors are given. resolution of issues etc. He will perform the role that was assigned to him based on the documentation provided by the moderator. the developer of the work product. They are categorized as follows: • Pre-walkthrough Activities • The developer of the work product schedules the walkthrough preferably. Here. He will try to discover defects in the work product. when and where they have to play the roles. The defect list is assigned to a person for repair. and answer questions that inspectors ask. • No counting or sandbagging. • Keep vested interest group apart. • Emphasize that the walkthrough is for error detection only and not error correction. the work product and corresponding documentation are given to a review team. • Holding a casual analysis meeting. and distributes the necessary documentation accordingly. The developer of the work product is present to explain the work product.

issues arise and presented but they should not find resolutions during the walkthrough. another walkthrough may be scheduled. formal technical reviews etc. Issues are listed down in the action list. Pressman provides a graphical representation of the software process. • He is asked to submit a status report on the action taken to resolve the errors or discrepancies listed in the action list. requirements management.• The developer of the work product gives a brief presentation of the work product. and other process models are based on this approach to development. It begins by analyzing the system. progressing to the analysis of the software. Framework of Activities These are activities that are performed by the people involved in the development process applicable to any software project regardless of project size.3 shows this type of software process model. coding. Task Sets Each of the activities in the process framework defines a set of tasks. • An action list is produced at the end of the walkthrough. it provides the framework from which a comprehensive plan for software development can be established. and the requirements of the software. deliverables or work products and software quality assurance (SQA) points. composition of the development team. They are also known as phases of the software development process. Figure 1. According to him. • Post-walkthrough Activities • The developer of the work product receives the action list. design. It suggests a systematic and sequential approach to the development of the software.
Types of Software Process Models
There are many types of software process models that suggest how to build software. Umbrella Activities These are activities that supports the framework of activities as the software development project progresses such as software project management. This is the first model ever formalized. • Possibly. and complexity of the problem. • He solicit comments from the reviewers. risk management. They are modified and adjusted to the specific characteristic of the software project. Common process models are discussed within this section. and the management and work products that are required. testing and maintenance. tasks sets and umbrella activities. It is chosen based on the nature of the project and application. methods and tools to be used. These tasks would have milestones. Linear Sequential Model The Linear Sequential Model is also known as the waterfall model or the classic life cycle. It insists that a phase can not begin unless the previous phase is finished. 9
. This may be omitted if the reviewers are familiar with the work product or project. It consists of framework activities.
The Software Process
The software process provides a strategy that a software development team employs in order to build quality software. change management. Sometimes.

The disadvantages of this process model are: • Customers may mistakenly accept the prototype as a working version of the software. it is very difficult to decide when one phase ends and the other begins. prototypes are built. • It provides a basis for other software process models. Software quality is compromised because other software requirements are not considered such as maintainability. processing. • End-user involvement only occurs at the beginning (requirements engineering) and at the end (operations and maintenance). or the form that human-computer interaction should take. or output requirements. In fact. The disadvantages of this model are: • Real software projects rarely follow a strict sequential flow. it delays the development of the software. The advantage of this process model is: • The end-users have an active part in defining the human-computer interaction requirements of the system. This approach is best suited for the following situations: • A customer defines a set of general objectives for the software but does not identify detailed input. • End-users sometimes have difficulty stating all of their requirements. They get the actual "feel" of the software. Thus.
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. Prototypes are partially developed software that enable end-users and developers examine aspects of the proposed system and decide if it is included in the final software product. • The developer may be unsure of the efficiency of an algorithm. the adaptability of a technology. It does not address the fact the requirements may change during the software development project.
Linear Sequential Model
Prototyping Model To aid in the understanding of end-user requirements.The advantages of this model are: • It is the first process model ever formulated.

The disadvantages of this model are: • For large but scalable projects. In this process model. • It is not a good process model for systems that require high performance.
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. It is best used for software projects where requirements are well-understood. The advantage of this model is: • A fully functional system is created in a short span of time. Everybody is expected to be committed to a rapid approach to development.• Developers tend to make implementation compromises in order to have a working prototype without thinking of future expansion and maintenance
Prototyping Model
Rapid Application Development (RAD) Model This process is a linear sequential software development process that emphasizes an extremely short development cycle. and big budget with resources are available. Functional partitions are assigned to different teams. project scope is properly constrained. It is achieved through a modularbased construction approach. the software project is defined based on functional decomposition of the software. • Developers and customers must be committed to the rapid-fire of activities necessary to develop the software in a short amount of time. and are developed in parallel. • It is not a good process model for systems that make use of new technology or high degree of interoperability with existing computer programs such as legacy systems. • It is not a good process model for systems that cannot be modularized. this process requires a sufficient number of developers to have the right number of development teams.

Specific evolutionary process models are Incremental Model. Spiral Model. The approach is iterative in nature. and Component-based Assembly Model. Linear sequences are defined where each sequence produces an increment of the software. Incremental Model This process model combines the elements of a linear sequential model with the iterative philosophy of prototyping. the increment is an operational product. Unlike prototyping. It enables the development of an increasingly more complicated version of the software.Rapid Application Development (RAD) Model
Evolutionary Process Models This process model recognizes that software evolves over a period of time.
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it requires risk assessment expertise.Incremental Model
Spiral Model It was originally proposed by Boehm.7 shows an example of a spiral model. An important feature of this model is that it has risk analysis as one of its framework of activities. It provides potential rapid development of incremental versions of the software. Figure 1. It is an evolutionary software process model that couples the iterative nature of prototyping with the controlled and systematic aspects of linear sequential model. Therefore.
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Spiral Model
Component-based Assembly Model It is similar to Spiral Process Model. However. it makes use of object technologies where the emphasis of the development is on the creation of classes which encapsulates both data and the methods used to manipulate the data. Reusability is one of the quality characteristics that are always checked during the development of the software.
Component-based Assembly Model
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Understanding systems provides a context for any project through the definition of the boundaries of the projects.Concurrent Development Model The Concurrent Development Model is also known as concurrent engineering. "What is included in the project? What is not?" In defining the system boundaries. It makes use of state charts to represents the concurrent relationship among tasks associated within a framework of activities. The user's need.
Formal Methods The Formal Methods is a software engineering approach which encompasses a set of activities that lead to mathematical specification of the software. It provides a mechanism for removing many of the problems that are difficult to overcome using other software engineering paradigm. do activities or receive output. Systems consists of a group of entities or components. either they provide input. discover and correct errors that might otherwise be undetected. It asks the question. and 15
. and working together to achieve a common goal. • a list of inputs. Factors that Affect the Choice of Process Model • Type of the Project • Methods and Tools to be Used • Requirements of the Stakeholders • Common Sense and Judgment
Understanding Systems
The software project that needs to be developed revolves around systems. It serves as a means to verify. a software engineer discovers the following: • entities or group of entities that are related and organized in some way within the system. • activities or actions that must be performed by the entities or group of entities in order to achieve the purpose of the system. It is represented schematically by a series of major technical tasks. and associated states. interacting together to form specific interrelationships. management decisions and review results drive the over-all progression of the development. organized by means of structure.

The goal of this system is to handle club membership application. Procedures. It is important to determine the boundaries of the systems and their interactions so that the impact of their development is minimal and can be managed and controlled. They are represented by an arrow with the name of the data being passed. Again. the more resources must be devoted to its everyday maintenance. This component is the policies and procedures that govern the operation of the automated system. Automated systems are examples of systems. They are not perfect. scheduling of mock try-outs and the assignment of the applicant to a squad. Because systems are composed of smaller subsystem and vice versa. They will always have areas for correctness and improvements. man-made systems and automated systems. and they can always be partitioned into smaller systems. the less it is able to adapt to different circumstances. Stakeholders and developers should be aware of the risks and costs of the changes during the development of the software. Man-made systems are also considered manual systems. they are represented by an arrow with the name of the data being passed. it consists of the following: 1.
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. namely. This component is the physical device. The major activities that are performed are the submission of the application forms. Computer Hardware. specifically. and they interpret the output (information) for day-to-day decisions. the squad listings.• a list of outputs. This would help the software engineer study the system where the software project revolves. The arrow head indicates the flow of the data. 5. It consists of components that supports the operation of a domain-specific system. This is the most important principle that a software engineer must understand. • The more specialized a system. Data and Information. club staff and coach. They are represented by a circle in the middle that defines the functionality of maintaining club membership information. They provide the data as input. Entities that are involved in this system are the applicant. This component is the program that executes within the machine. • The larger the system is. Computer Software. As an example. They are represented as rectangular boxes. software systems can be developed in a modular way. These areas for correctness and improvements can be addressed by automated systems. They are related with one another by performing certain activities within this system. a list of inputs are necessary. application forms and the schedule of the mock try-outs. The results that are expected from this system are the membership reports and importantly. General Principles of Systems Some general principles of systems are discussed below. • Systems are always part of larger systems. This component is responsible for the use of the computer hardware and software. In general. This component provides the input (data) and output (information). 3. To perform these actions. Changes would have a great impact on the development of such systems. The arrow head indicates the flow of the data. 4. the cost of maintaining a mainframe is very expensive compared to maintaining several personal computers. One should be carefully that there is no dramatic changes in the environment or requirements when the software is being developed. Components of Automated Systems There are two types of systems. People. 2.

specifically. This component allows the connection of one computer system with another computer system. It is also known as the network component.6. Much of the requirements will be coming from this group.
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. there are two major groups that are involved in the software development effort. particularly. Those who are directly involved Table 1 shows the categorization of the end-users according to the job functions that they perform within the system. In this section. Connectivity. their interest regarding the system and the software that needs to be developed. They can be grouped into two according to their involvement within the system organization and development. End-users End-users are the people who will be using the end-product. those who are directly involved and those who are indirectly involved.
Understanding People in the Development Effort
To help in the fostering of a quality mindset in the development of the software. namely. end-users and development team. one should understand the people involved in the software development process.

They are good candidates for interview regarding the report layouts and code design.Table 1 General Guidelines with End-Users • The higher the level of the manager. funding or time that the users feel is necessary to build an effective system. try to discover areas of commonality.Requirements Engineering. More on this on Chapter 3. As software engineer. Resource and financial constraints will occur. • Management may not provide resources. the less he or she is likely to care about computer technology. 18
. This can be seen based on their different levels of concerns.Requirements Engineering. It would be best to ask him or her over-all results and performance the system can provide. It is important to prioritize requirements. More on this on Chapter 3. • The goals and priorities of management may be in conflict with those of the supervisory and operational users.

• Standards developed by other departments within the organization or by the customer or user who will inherit the system • Various standards imposed by the government regulatory agencies. these group includes the auditors. The general objective of this group is to ensure that the system is developed in accordance with various standard set such as: • Accounting standards developed by the organization's accounting operations or firm. programmer and testers. Programmers Based on the system design. Testers For each work product. prototypes. System Designer His job is to transform a technology free architectural design that will provide the framework within which the programmers can work. examples are brochures. There are several types of documentation and informational work products. • They are more interested in substance rather than form. They may be needed in the definition of the presentation and documentation of the system. keep an eye on them and address them accordingly.
Documentation in the Development Effort
What is documentation? It is a set of documents or informational products to describe a computer system. Each document is designed to perform a particular function such as: • REFERENCE. Some possible problem that may be encountered with this group. Some of them are listed below: 19
. he identifies customer wants. • MOTIVATIONAL. It ensures that work products meet requirements and standards defined. it should be reviewed for faults and errors. the quality assurance group. prototypes etc. It is important that they be involved in every activity that would require their expertise and opinion. It may consists of the following: systems analyst. the system analyst and designer are the same person but it must be emphasized that the functions require different focus and skill. examples are tutorials. Usually. • They provide the necessary notation and format of documentation. demonstrations. and quality assurance group. and documents and prioritizes requirements. • They don't get involved in the project until the very end. This involves breaking down the system to determine specific requirements which will be the basis for the design of the software. examples are technical or functional specifications • INSTRUCTIONAL. demonstrations. systems designer. standard bearers. This supports the quality culture needed to developed quality software. Within this system. As software engineers. the programmers write the codes of the software using a particular programming language.Those who are indirectly involved Mostly. System Analyst His responsibility is understanding the system. Development Team The development team is responsible in building the software that will support a domain specific system. particularly.

manuals and technical documents serve as written backup. provide a legend. clerical and automated procedures. programs and procedures. It should be written in a fluent and easy-to-read style and format. 3. • They serve as security blankets. and target audience (who will be using the document). a purpose or objective. It provides a description of details that cannot be directly inferred from the software itself or from executable work products.system test scripts and models. It should be accurate and complete. Accessibility. It should be easy to find the information that users want. • They serve as tangible deliverables. Good manuals differentiate their products.especially. hands-on training for new personnel and design aid. • They serve as contractual obligations. It must be present when and where needed. Each item of documentation should have a unique name for referencing and cross-referencing. Suitability. 2. and retrieval. 4. storage. It should not have any abbreviations. Related documents must be located in one manual or book. • They serve as sales and marketing tools.
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.5in x 11in paper for ease of handling. It is important to include the following items as part of the user's manual. In case people leave. Management and users know little about computer jargons. Referrals to other manuals and books should be avoided. but they can hold and see a user manual. for off-the-shelf software products. Availability. and maintain the system. Important of Documents and Manuals Documents and manuals are important because: • They save cost. It serves to communicate the system's architectural versions. It should be aligned to users tasks and interests. It should fit in an ordinary 8. It should be understandable without further explanation. • They serve as testing and implementation aids. Users should know that the documents exists. • They are used to compare the old and new systems. one needs less personnel to train the users. With good manuals. Some criteria for measuring usability of documents are listed below: 1.a slick manual means a slick product. Readability.Criteria for Measuring Usability of Documents A useful document furthers the understanding of the system's desired and actual behavior and structure. If you must use one. support on-going operations.

CHAPTER 2

Requirements Engineering
Designing and building a computer system is challenging, creative and just plain fun. However, developing a good software that solves the wrong problem serves no one. It is important to understand user's needs and requirements so that we solve the right problem and build the right system. In this chapter, we will be discussing the concepts and dynamics of requirements engineering. It is a software development phase that consists of seven distinct tasks or activities which has a goal of understanding and documenting stake holder's requirements. Two important models will be built, namely, requirements model which is the system or problem domain model, and the analysis model which serves as the base model of the software (solution model). The Requirements Traceability Matrix (RTM) will be introduced to help software engineers manage requirements, and the requirements metrics and its significance will also be discussed. Requirements Engineering Concepts Requirements Engineering allows software developers to understand the problem they are solving. It encompasses a set of tasks that lead to an understanding of what the business impact of the software will be, what the customer wants, and how end-user will interact with the software. It provides an appropriate mechanism for understanding stake holder's needs, analyzing requirements, determining feasibility, negotiating a reasonable solution, specifying the solutions clearly, validating specification and managing requirements as they are transformed into a software system. Significance to the Customer, End-users, Software Development Team and Other Stakeholders Requirements Engineering provides the basic agreement between end-users and developers on what the software should do. It is a clear statement on the scope and boundaries of the system to be analyzed and studied. It gives stakeholders an opportunity to define their requirements understandable to the development team. This can be achieved through different documents, artifacts or work products such as use case models, analysis models, features and functions list, user scenarios etc. Designing and building an elegant computer program that solves the wrong problem is a waste. This is the reason why it is important to understand what customer wants before one begins to design and build a computer-based system. Requirements Engineering builds a bridge to design and construction. It allows the software development team to examine: • the context of the software work to be performed • the specific needs that design and construction must address • the priorities that guide the order in which work is to be completed • the data, functions and behaviors that will have a profound impact on the resultant design Requirements Engineering, like all other software engineering activities, must be adapted to the needs of the process, projects, products and the people doing the work. It is an activity that starts at inception until a base model of the software can be used at the design and construction phase. Requirements Engineering Tasks There are seven distinct tasks to requirements engineering, namely, inception, elicitation, elaboration, negotiation, specification, validation and management. It is 22

important to keep in mind that some of these tasks occurs in parallel and all are adapted to the needs of the project. All strive to define what customer wants, and all serve to establish a solid foundation for the design and construction of what the customer needs. Inception In general, most software projects begin when there is a problem to be solved, or an opportunity identified. As an example, consider a business that discovered a need, or a potential new market or service. At inception, the problem scope and its nature is defined. Software engineer asks a set of context free questions with the intent of establishing a basic understanding of the problem, people who want the solution, the nature of the solution, and the effectiveness of the preliminary communication and collaboration between end-users and developers. Initiating Requirements Engineering Since this is a preliminary investigation of the problem, a Q&A (Question and Answer) Approach or Interview is an appropriate technique in understanding the problem and its nature. Enumerated below are the recommend steps in initiating the requirements engineering phase. STEP 1: Identify stakeholders. A stakeholder is anyone who benefits in a direct or indirect way from the system which is being developed. The business operations managers, product managers, marketing people, internal and external customers, endusers, and others are the common people to interview. It is important at this step to create a list of people who will contribute input as requirements are elicited. The list of users will grow as more and more people get involved in elicitation. STEP 2: Recognize multiple viewpoints. It is important to remember that different stakeholder would have a different view of the system. Each would gain different benefits when the system is a success; each should have different risks if the development fails. At this step, categorize all stakeholder information and requirements. Also, identify requirements that are inconsistent and in conflict with one another. It should be organized in such a way that stakeholders can decide on a consistent set of requirements for the system. STEP 3: Work toward collaboration. The success of most projects would rely on collaboration. To achieve this, find areas within the requirements that are common to stakeholders. However, the challenge here is addressing inconsistencies and conflicts. Collaboration does not mean that a committee decides on the requirements of the system. In many cases, to resolve conflicts a project champion, normally a business manager or senior technologist, decides which requirements are included when the software is developed. STEP 4: Ask the First Question. To define the scope and nature of the problem, questions are asked to the customers and stakeholders. These questions may be categorized. As an example, consider the following questions: Stakeholder's or Customer's Motivation: 1. Who is behind the request for this work? 2. Why are they requesting such a work? 23

3. Who are the end-users of the system? 4. What are the benefits when the system has been developed successfully? 5. Are there any other ways in providing the solution to the problem? What are the alternatives. Customer's and Stakeholder's Perception: 1. How can one characterized a "good" output of the software? 2. What are the problems that will be addressed by the software? 3. What is the business environment to which the system will be built? 4. Are there any special performance issues or constraints that will affect the way the solution is approached? Effectiveness of the Communication: 1. Are we asking the right people the right questions? 2. Are the answers they are providing "official"? 3. Are the questions relevant to the problem? 4. Am I asking too many questions? 5. Can anyone else provide additional information? 6. Is there anything else that I need to know? Inception Work Product The main output or work product of inception task is a one- or twopage(s) of product request which is a paragraph summary of the problem and its nature. Elicitation After inception, one moves onward to elicitation. Elicitation is a task that helps the customer define what is required. However, this is not an easy task. Among the problems encountered in elicitation are discussed below: 1. Problems of Scope. It is important that the boundaries of the system be clearly and properly defined. It is important to avoid using too much technical detail because it may confuse rather than clarify the system's objectives. 2. Problems of Understanding. It is sometimes very difficult for the customers or users to completely define what they needed. Sometimes they have a poor understanding of the capabilities and limitations of their computing environment, or they don't have a full understanding of the problem domain. They sometimes may even omit information believing that it is obvious. 3. Problems of Volatility. It is inevitable that requirements change overtime. To help overcome these problems, software engineers must approach the requirements gathering activity in an organized and systematic manner. Collaborative Requirements Gathering Unlike inception where Q&A (Question and Answer) approach is used, elicitation makes use of a requirements elicitation format that combines the elements of problem solving, elaboration, negotiation, and specification. It requires the cooperation of a group of endusers and developers to elicit requirements. They work together to: • identify the problem • propose elements of the solution • negotiate different approaches • specify a preliminary set of solution requirements Joint Application Development is one collaborative requirement gathering technique that is popularly used to elicit requirements. 24

6. namely. 5. 8. Each will be working to develop the mini-specifications for one or more entries on the consensus list. The mini-specification is simply an elaboration of the item in the list using words and phrases. joint meeting tasks and post-joint meeting tasks. Invite the members of the team which may be the software team. accuracy etc. presents its mini-specification to all attendees. The consensus list in each topic area (objects. If there is no product request. The combined list from the previous task is shortened. 3. adds new ideas that come up during the discussion. Everyone should agree that the product is justified. customers. time and date of the meeting. pre-joint meeting tasks. it will uncover new objects. Select a facilitator. a combined list is created. 6. or performance requirements that will added to the original lists. or reworded to reflect the product or system to be developed. Once the consensus list is defined. It eliminates redundant entries. An issue list is maintained and they will be acted on later. After each mini-specification is completed. but does not delete anything. 2. constraints and performance) is defined. lengthen. A consensus list of validation criteria is created. one stakeholder should write one. the team is divided into sub-teams. 9. 2. 3. Compile the complete draft specifications of the items discussed in the meeting. Joint Meeting Tasks 1. size and business rules • a list of performance criteria such as speed. Set the place. 4. Each participant presents his list to the group. Pre-Joint Meeting Tasks 1. Post-Joint Meeting Tasks 1.The tasks involved in elicitation may be categorized into three groups. Prioritize the requirements. each attendee makes a list of validation criteria for the product or system and presents the list to the team. and other stakeholders). The first topic that needs to be resolved is the need and justification of the new product. 4. deletions and further elaboration are made. Each sub-team. services. then. issues arise that cannot be resolved during the meeting.
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. One or more participants is assigned the task of writing a complete draft specification using all inputs from the meeting. In some cases. 5. After all participants presents. Each attendee is asked to make the following: • a list of objects that are part of the environment that surrounds the system • a list of other objects that are produced by the system • a list of objects that are used by the system to perform its functions • a list of services (processes or functions) that manipulate or interact with the objects • a list of constraints such as cost. In some cases. One can use the Quality Function Technique or MoSCoW Technique. Additions. Distribute the product request to all attendees before the meeting. constraints. 2. services. Note that the list are not expected to be exhaustive but are expected to reflect the person's perception of the system. 7.

Then. deploy these values throughout the engineering process. It means that if the requirements are present. With the succeeding meetings with the team. namely. and ease of software installation. It identifies three types of requirements: 1 . 3 . function deployment. overall operation correctness and reliability. Exciting Requirements These requirements reflect features that go beyond the customer's expectations and prove to be very satisfying when present. the customer is satisfied. From the value analysis. Expected Requirements These requirements are implicit to the product or system and may be so fundamental that the customer does not explicitly state them. Normal Requirements These requirements directly reflect the objectives and goals stated for a product or system during meetings with the customer. Information deployment identifies both data objects and events that the system must consume and produce. and task deployment. Examples of expected requirements are ease of human or machine interaction. 2 . Function deployment is used to determine the value of each function that is required for the system.Quality Function Deployment Quality Function Deployment is a technique that emphasizes an understanding of what is valuable to the customer. each requirements are categorized based on the three types of requirements. MoSCoW Technique Each requirement can be evaluated against classes of priority as specified in the table below During the software engineering process. a short meeting should be conducted to review and probably. value analysis is conducted to determine the relative priority of requirement based on three deployments. information deployment.
Classification of Priorities
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. This is related to a function. The absence of these requirement may cause for significant dissatisfaction. reassign priorities. Task deployment examines the behavior of the product or system within the context of its environment.

e. For a successful software development project.
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. preferably. The Art of Negotiation Negotiation is a means of establishing collaboration. Elaboration Work Product The requirements model and the analysis model are the main work product of this task. and Requirements Specifications section of this chapter. The purpose of negotiation is to develop a project plan that meets the requirements of the user while reflecting real-world constraints such as time. requirements are ranked. and the software team is able to realistically work towards meeting deadlines and budgets. redefining and refining of models. people and budget. • A description of the system's technical environment • A priority list of requirements. stakeholders and software development team reconcile conflicts. Conflicts arise when customers are asking for more than what the software development can achieve given limited system resources. users. business domain entities that are visible to the end-user. Negotiation In negotiation. functional and behavioral domain of the problem. The relationships and collaboration between classes are identified and a variety of supplementary UML diagrams are produced. The end-result of elaboration is an analysis model that defines the informational. For most systems. customers. and other stakeholders who participated in requirements elicitation. This requirement engineering task focuses on defining. collaboration is a must. It means that customer gets the system or product that satisfies majority of the needs. objects and domain constraints that apply to each Elaboration The information obtained from the team during inception and elicitation is expanded and refined during elaboration. The attributes of each analysis class are defined and responsibilities that are required by each class are identified. in terms of functions..Elicitation Work Product The output of the elicitation task can vary depending on size of the system or product to be built. namely. It tries to model the "WHAT" rather than the "HOW". the output or work products include: • A statement of need and feasibility • A bounded statement of scope for the system or product • A list of customer. It describes how the endusers and actors interact with the system. i. The requirements model is created using methodologies that capitalizes on user scenarios which define the way the system is used. estimates on development effort and costs are made. The development of these models will be discussed in the Requirements Analysis and Model. risk associated with each requirements are identified and analyzed. To resolve these conflicts. the requirements model (system or problem domain) and analysis model (solution domain). Below are some guidelines in negotiating with stakeholders. The analysis model is derived from the requirements model where each scenario is analyzed to get the analysis classes. and delivery time set.

Remember that negotiation is not competition. Is each requirement bounded and clear? 5. missing information. a set of graphical models. Don't be afraid to think out of the box. It shows the informational. Have all requirements been specified at the proper level of abstraction? That is. particularly. Does each requirement have attribution? That is. commit to the agreement and move on to other matters. Listen effectively. functional and behavioral aspects of the system. They look for errors in content or interpretation. users. It can be written down as a document. a prototype or any combination of these. everybody should feel that their concerns have been addressed. Be ready to commit. the design and construction of the software. do some requirements provide a level of technical detail that is not appropriate at the stage? 3. 2. Listening shows that you are concern. and other stakeholders. The requirements are prioritized and grouped within packages that will be implemented as software increments and delivered to the customer. 6. Requirements Validation Checklist As the models are built. It checks the conformance work products to the standards established in the software project. Decide on how we are going to make everything happen.1. Once an agreement has been reached. Listen to what the parties want to achieve. a specific individual) noted for each requirement? 6. and ambiguity. 7. 3. 4. omissions. Be creative. and errors have been detected and corrected. Focus on the other party's interest. customers. Focus on the problem that needs to be solved. is a source (generally. omission. Validation The work products produced as a consequence of requirements engineering are assessed for quality during validation step. Is the requirement really necessary or does it represent an add-on feature that may not be essential to the objective of the system? 4. It examines the specification to ensure that all software requirements have been stated clearly and that inconsistencies. Is each requirement consistent with the overall objective for the system or product? 2. a formal mathematical model. areas where clarification is required. inconsistencies. The models serves as your specifications. Try not to formulate your response or reaction while the other is speaking. It serves as the foundation for subsequent software engineering activities. conflicting and unrealistic requirements. You might get something that can help you negotiate later on. 5. Everybody should compromise. Do any of the requirements conflict with other requirements? 28
. The review team that validates the requirements consists of software engineers. Don't make it personal. Questions as suggested by Pressman are listed below to serve as a guideline for validating the work products of the requirement engineering phase. At some level. Specification A specification is the final artifact or work product produced by the software engineer during requirements engineering. 1. they are examined for consistency. Have a strategy. Don't take hard positions if you want to avoid conflict. or that they have achieved something.

function and behavior of the system to be built? 10.Has the requirements model been "partitioned" in a way that exposes progressively more detailed information about the system? 11. traceability tables are developed. Each requirement is assigned a unique identifier. The Requirements Model Rational Rose defines the Requirements Model as illustrated below. control. specifically. Supplementary Specifications. It consists of three elements. Management It is a set of activities that help the project team identify.7.Have the requirements pattern been used to simplify the requirements model? Have all patterns been properly validated? Are all patterns consistent with customer requirements? These and other questions should be asked and answered to ensure that all work products reflect the customer's needs so that it provides a solid foundation for design and construction. Does the requirement model properly reflect the information. information obtained during inception and elicitation is expanded and refined to produce two important models. we will be discussing the requirements model and how it is built. Requirements management starts once they are identified.
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.requirements model and analysis model. Is each requirement achievable in the technical environment that will house the system or product? 8. Is each requirement testable. Once requirements have been identified. In this section. and Glossary. Requirements Analysis and Model During elaboration. The Requirements Traceability Matrix (RTM) is discussed in the Requirements Traceability Matrix section of this chapter which will help software engineers manage requirements as the development process progresses. Use Case Model. and track requirements and their changes at any time as the project progresses. once implemented? 9. The requirements model provides a model of the system or problem domain.

The use case diagram consists of actors and use cases. The Use Case Model consists of two parts. The use case specifications are textual documents that specify properties of the use cases such as flow of events.Requirements Model Use Case Model It is used to describe what the system will do. This is used by the developers to establish a common dialect with customers and end-users. namely. Supplementary Specifications It contains those requirements that don't map to a specific use case. usability. They may be nonfunctional requirements such as maintainability of the source codes. It serves as a contract between the customers. It is an important complement to the Use Case Model because with it we are able to specify a complete system requirements.
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. or system constraints that restricts our choices for constructing a solution to the problem such as the system should be developed on Solaris and Java. post-conditions etc. There should only be one glossary per system. it is used to ensure that what they build is what is expected. it is used to validate that the system will become what they expect it to be. performance. 1. Glossary It defines a common terminology for all models. end-users and system developers. For the developers. tool used to define the Use case Model is the Use case Diagram. For customers and end-users. and supportability. reliability. the use case diagrams and use case specifications. pre-conditions. It shows the functionality that the system provides and which users will communicate with the system. Each use case in the model is describe in detail using the use case specifications.

Scenarios are instances of the functionality that the system provides.Scenario Modeling The Use Case Model is a mechanism for capturing the desired behavior of the system without specifying how the behavior is to be implemented. It is important to note that building the model is an iterative process of refinement. The point of view of the actors interacting with the system are used in describing the scenarios.
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. Use Case Diagram of UML As was mentioned in the previous section. Generalization or specialization follows the same concepts that was discussed in object oriented concepts. It captures the specific interactions that occur between producers and consumers of data. and the system itself. They are shown by using a keyword in matched guillemets (<<>>) such as <<extend>> and <<include>>. the Use Case Diagram of UML is used as the modeling tool for the Use case Model.
Use Case Diagram Basic Notation The Use Case Model can be refined to include stereotypes on associations and generalization of actors and use cases. Stereotypes in UML is a special use of model elements that is constrained to behave in a particular way.

club staff and coach.Use Case Diagram Expanded Notation Developing the Use Case Model STEP 1: Identify actors. It may be a person.
Club Membership Maintenance Actors Two actors were identified. Remember that use cases are sequence of actions that yields an observable result to actors. the image below identifies the initial use cases. namely. Identify the external actors that will interact with the system. device or another system. STEP 2: Identify use cases.
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. As an example. As an example. the figure below identifies the actors for the Club Membership Maintenance of the case study. Identify use cases that the system needs to perform.

The figure below shows the first iteration of the use case model. • Add Athlete Record • Edit Athlete Record • Delete Athlete Record • Update Athlete's Status STEP 3: Associate use cases with actors.
First Iteration of Club Membership Use Case Model STEP 4: Refine and re-define the model.Club Membership Maintenance Use Cases The following use cases were identified. The second iteration of the use case model is seen in the figure below. Optionally. The identified use cases are distributed to the two actors. number the use cases. 33
. This use case can be refined by using the enhanced notation.

The Maintain Athlete Record Use Case is extended to have the following option: • 1.3 Remove Athlete Record Every time Update Athlete's Record Use Case is performed. The use case specification is a document where the internal details of the use case is specified. the firstfive are the recommended sections. For each use case found in the Use Case Model. the another use case was added to specify that certain actors can view the athlete's record (View Athlete Record Use Case).1 Add Athlete Record • 1. an Edit Athlete Record is also performed. This is being managed by the club staff. The decision when to stop iterating is a subjective one and is done by the one modeling. However. 34
. consider answering questions found in the Requirements Model Validation Checklist. write the use case specification. Stereotypes on associates are used to include or extend this use case. the use case specification must be defined. Also.Second Iteration Club Membership Use Case Model In the second iteration. Modeling is an iterative process. It can contain any of the listed sections below.2 Edit Athlete Record • 1. elaboration is done by introducing the Maintain Athlete Record Use Case. STEP 5: For each use case. To help in the decision-making.

It uses the following notation. Flow of Events. they are the extend or include use cases. These are events that describes what the use case is doing. The basic flow is the common work flow that the use case follows. An instance of the functionality of the system is a scenario. The flow of events contains the most important information derived from use case modeling work. This is the most important part of the requirements analysis part. Special Requirements. However. Post-conditions.1. It should be the same as the name found in the Use Case Model. Pre-conditions. 3. it is used to model each scenario of the use case. 4. NOT how the system is design to perform. Other Diagrams. The flow of events of a use case consists of a basic flow and several alternative flows.
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. odd cases and exceptional flows handling error situations. Normally. There are two ways in expressing the flow of events. one uses the Activity Diagram of UML. Name. other use case that are associated with the current use case are specified here. It is used similar to the Flowchart. In this section. Here. 8. we have one basic flow while the alternative flow addresses regular variants. scenarios are identified.textual and graphical. Brief Description. 2. It describes the role and purpose of the use case using a few lines of sentences. Relationships. It specifies the conditions that exist after the use case ends. It is also describe as one flow through a use case. It specifies the conditions that exist before the use case starts. It contains other requirements that cannot be specified using the diagram which is similar to the non-functional requirements. It provides a description of a sequence of actions that shows what the system needs to do in order to provide the service that an actor is expecting. 6. 5. This is the name of the use case. It describes essentially what the use case is specifically doing. normally. sketches of dialog of users with the system etc. 7. To graphically illustrate the flow of events. Additional diagrams to help in clarifying requirements are placed in this section such as screen prototypes.

Activity Diagram Notation The figure below is an example of an activity diagram. It illustrates how athletes are initially assigned to a squad. The club staff gets the filled up application form from the athletes and they prepare the mock try-out area. During the try-outs, the selection committee evaluates the performance of the athletes. If the athlete plays excellently, they are immediately assigned to the Competing Squad. Otherwise, they are assigned to the Training Squad. The club staff will keep the athlete records on the appropriate files.

Initial Athlete Squad Assignment The activity diagram can be modified as a the swimlane diagram. In this diagram, activities are aligned based on the actors who have responsibility for the specified activity. The figure below is the modified activity diagram where the actors responsible for the activity is drawn above the activity symbols.

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Initial Athlete Squad Assignment using Swimlane Diagram To help software engineers in defining the flow of events, a list of guidelines is presented below. 1. To reinforce actor responsibility, start the description with "When the actor...". 1. Describe the data exchange between the actor and the use case. 2. Try not to describe the details of the user interface unless needed. 3. Answer ALL "what" questions. Test designers will use this text to identify test cases. 4. Avoid terminologies such as "For example,...", "process" and "information". 5. Describes when the use case starts and ends. 37

STEP 6: Refine and re-define the use case specifications. Similar with developing the Use Case Model, one can refine and re-define the use case specification. It is also done iteratively. When to stop depends on the one modeling. One can answer the questions presented in the Requirements Model Validation Checklist to determine when to stop refining and redefining the use case specifications. Requirements Model Validation Checklist Like any work product being produced at any phase, validation is required. Listed below are the questions that guides software engineers to validate the requirements model. It is important to note at this time that the checklist serves as a guide. The software engineer may add or remove questions depending on the circumstances and needs of software development project. Use Case Model Validation Checklist 1. Can we understand the Use Case Model? 2. Can we form a clear idea of the system's over-all functionality? 3. Can we see the relationship among the functions that the system needs to perform? 4. Did we address all functional requirements? 5. Does the use case model contain inconsistent behavior? 6. Can the use case model be divided into use case packages? Are they divided appropriately? Actor Validation Checklist 1. Did we identify all actors? 2. Are all actors associated with at least one use case? 3. Does an actor specify a role? Should we merge or split actors? 4. Do the actors have intuitive and descriptive names? 5. Can both users and customers understand the names? Use Case Validation Checklist 1. Are all use case associated with actors or other use cases? 2. Are use cases independent of one another? 3. Are there any use cases that exhibit similar behavior or flow of events 4. Are use cases given a unique, intuitive or explanatory names? 5. Do customers and users alike understand the names and descriptions of the use cases? Use Case Specification Validation Checklist 1. Can we clearly see who wishes to perform a use case? 2. Is the purpose of the use case also clear? 3. Is the use case description properly and clearly defined? Can we understand it? Does it encapsulate what the use case is supposed to do? 4. Is it clear when the flow of events starts? When it ends? 5. Is it clear how the flow of events starts? How it ends? 6. Can we clearly understand the actor interactions and exchanges of information? 7. Are there any complex use cases? Glossary Validation Checklist 1. Is the term clear or concise? 2. Are the terms used within the use case specification? 38

synonyms?
3. The following guide questions can be used. and documented? 2. It attempts to whitebox the development approach. Is the class a well-defined abstraction? 5. namely. Are all diagrams traceable to the requirements? Requirements Traceability Matrix (RTM) The Requirements Traceability Matrix (RTM) is a tool for managing requirements that can be used not only in requirements engineering but through out the software engineering process. Is the number of classes reasonable? 3. conceptual. The whitebox approach refers to the development of system requirements without considering the technical implementation of those requirements. Does the class have a name indicative of its role? 4. specification and implementation. Are the relationships clear and consistent? 4. concepts within the domain of the case study are athletes. Those listed in the table below are the recommended initial elements of the RTM. coaches. Components of Requirements Traceability Matrix There are many variations on the components that make up the RTM. Are the terms used consistently within the system? Are there any
Analysis Model Validation Checklist Similar with the Requirements Model. There are three. Are all scenarios been handled and modeled? (Including exceptional cases) 2. The Specification Perspective deals with interfaces. Object Model 1. The Conceptual Perspective deals with the “concepts in the domain”. But in terms of requirements. Are all analysis classes identified. we deal with the conceptual and specification. Is the class traceable to a requirement? Behavioral Model 1. Are the interaction diagrams clear? 3. Similar with UML. Are messages well-defined? 5. Interfaces deal with how the concepts (system elements) interact with one another such as promoting or demoting an athlete. defined.
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. this approach uses the concept of perspectives. Are all attributes and responsibilities defined for a class? Are they functionally coupled? 6. As an example. squad and teams. a validation is required.

One may add other elements. This is really where the power of the RTM is reflected.Initial RTM Components While the above elements are the initial RTM.
Additional RTM Components 40
. one can customize the matrix to tie the requirements with other work products or documents.

Also. The requirements work products can be evaluated by looking first at the number of requirements. iterate back to the requirements engineering phase. It can be used to determine if the requirements are ready to be turned over to them. Similarly. a thorough understanding of the requirements should be done. project and product. It grows as the project moves along. the requirement size can be tracked down. you can use all components. The Requirements Profile Test is a
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.The components and the use of the RTM should be adapted to the needs of the process. it gives an indication how large the software project is. A large number of changes indicates some instability and uncertainty in our understanding of what the system should do or how it should behave. Example of a RTM:
Example of a RTM Requirements Metrics Measuring requirements usually focuses on three areas: process. As software engineers. In such a case. remove components or add components as you seem fit. Requirement size can be a good input for estimating software development effort. product and resources. As the number grows. one can measure the number of times that the requirements have changed. we would have a deeper understanding of the problem and solution which could lead to uncovering requirements that were not apparent during the requirements engineering process. Requirements can be used by the designers and testers. As design and development occur. as the software development progresses. possibly.

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. they are asked to rate each requirement on a scale of 1 to 5 based on a system as specified in the table below:
System Designer Scale Description For testers. For the designers. they are asked to rate each requirement on a scale of 1 to 5 based on the a system as specified in the table below.technique employed to determine the readiness to turn over requirements to the designers or testers3.

the scores can provide useful information that encourages you to improve the quality of the requirements before design proceeds. However. requirements need to be reassessed and rewritten. Otherwise. You need to iterate back to the requirement engineering phase.
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. the requirements can be passed on the designers and testers.System Tester Scale Description If the result of the requirement's profile resulted with 1's and 2's. Assessment is subjective.

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. component-level design. that consists of good design components. Creativity is required for the formulation of a product or system where requirements (end-users and developers) and technical aspects are joined together.e. and components. The design metrics will also be discussed. 2. 3. 8. from a higher level of abstraction to lower levels of abstraction. The design should have interfaces that reduces the complexity of the links between components and the environment.
CHAPTER 3 Design Engineering
Design Engineering Concepts
Design Engineering is the most challenging phase of the software development project that every software engineer experience. process or system in sufficient detail to permit its physical realization. 5. design engineering focuses on the creation of a representation or model that are concentrated on architecture of the software.. The design should be modular that are logically partitioned into subsystems and elements. interface design. The design should use a notation that convey its meaning. function and behavior. The design of the components should have independent functional characteristics. The design process is an iterative process of refinement. Pressman suggests a list of quality guidelines as enumerated below4. data design. 1. Specifically. architecture. The design should consists of unique data representations. all implicit requirements desired by the end-user and developers. 6. 7. data structures. interfaces and components that are necessary to implement the software. In this chapter. It sets a stage where construction and testing of software is done. interfaces. The design should have a recognizable architecture that has been created using known architectural styles or patterns. The design is derived from using a method repetitively to obtain information during the requirements engineering phase. Each representation must be traced back to a specific requirement as documented in the RTM to ensure quality of design. at the same time. function and behavior from an implementation perspective. It is the last software engineering phase where models are created. 4. i. It uses various techniques and principles for the purpose of defining a device. • be readable and understandable by those who will generate the code and test the software. The design of the data structure should lead to the design of the appropriate classes that are derived from known data patterns. systematic methodology and thorough review. and • provide an over-all illustration of the software from the perspective of the data. The above guidelines encourages good design through the application of fundamental design principles. the design should: • implement all explicitly stated requirements as modeled in the analysis model. and that can be created in an evolutionary manner. We will also learn what elements of the RTM are modified and added to trace design work products with the requirements.Unlike Requirements Engineering which creates model that focuses on the description of data. It produces a design model that translates the analysis model into a blueprint for constructing and testing the software. we will learn the design concepts and principles.

Interaction Coupling is the measure of the number of message types an object sends to another object. 2. At the higher level of abstraction. namely. For object-oriented design. 1. three types of cohesion are used. enforces access constraints on data and procedural details. we define different levels of abstractions as we design the blueprint of the software. 45
. Abstraction When designing a modular system. For object-oriented design. Modules and classes communicate through interfaces. When we iterate to much lower level of abstractions. Functional Independence is the characteristic of a module or class to address a specific function as defined by the requirements. This limits or controls the propagation of changes and errors when modifications are done to the modules or classes. It provides a necessary framework of creating the design work products right. two types of coupling are used. Modularity also encourages functional independence. accommodate changes easily.Design Concepts
Design concepts provides the software engineer a foundation from which design methods can be applied. In object-oriented approach. Two types of abstractions are created. They are achieved by defining modules that do a single task or function and have just enough interaction with other modules. Data abstractions refer to the named collection of data that describes the information required by the system. a detailed description of the solution is defined. test and debug effectively. many level of abstractions are used. and maintain the system with little side-effects. They are named and addressable components when linked and working together satisfy a requirement. data abstractions and procedural abstractions. One minimize the number of attributes and operations that are unnecessarily inherited. The software is decomposed into pieces called modules. Coupling is the degree of interconnectedness between design objects as represented by the number of links an object has and by the degree of interaction it has with other objects. and the number of parameters passed with these message types. As software engineers. Good interaction coupling is kept to a minimum to avoid possible change ripples through the interface. Modularity leads to information hiding. Cohesion is the measure to which an element (attribute. Good design uses two important criteria: coupling and cohesion. Procedural abstractions refer to the sequences of commands or instructions that have a specific limited actions. Inheritance Coupling is the degree to which a subclass actually needs the features (attributes and operations) it inherits from its base class. or class within a package) contributes to a single purpose. Design is modularized so that we can easily develop a plan for software increments. Modularity Modularity is the characteristic of a software that allows its development and maintenance to be manageable. operation. thus. Information hiding means hiding the details (attributes and operations) of the module or class from all others that have no need for such information. they are called classes. we state the solution using broad terms.

Inheritance definition should reflect true inheritance rather than sharing syntactic structure. Report and form layouts are included. Refinement helps the software engineer to uncover the details as the development progresses. It helps the software engineer in creating a complete design model as the design evolves. subsystems and components. Operation Cohesion is the degree to which an operation focuses on a single functional requirement. Architectural Design This refers to the overall structure of the software.
The Design Model
The work product of the design engineering phase is the design model which consists of the architectural design. Of particular interest are the control classes. interface design and component-level design.1. Entity classes that are defined in the requirements engineering phase are refined to create the logical database design. During refactoring. data design. Component-level Design This refers to the design of the internal behavior of each classes. It uses the class diagrams and component diagrams. the design model is checked for redundancy. 2. It is a process of changing the software so that the external behavior remains the same and the internal structures are improved. It represents layers. inefficient or unnecessary algorithms. Data Design This refers to the design and organization of data. Persistent classes are developed to access data from a database server. particularly. the human-interaction aspects. It uses the class diagram and state transition diagrams. Class Cohesion is the degree to which a class is focused on a single requirement. Specialization Cohesion address the semantic cohesion of inheritance. These are corrected to produce a better design. Abstraction complements refinement as they enable a software engineer to specify the behavior and data of a class or module yet suppressing low levels of detail. It is modeled using the package diagram of UML. Refactoring Refactoring is a technique that simplifies the design of the component without changingits function and behavior. unused design elements. This is the most important design because the functional requirements are represented by these classes. It is modeled using the class diagram. 3. Good design produces highly cohesive operations. Interface Design This refers to the design of the interaction of the system with its environment. Refinement Refinement is also known as the process of elaboration. Deployment-level Design 46
. poorly constructed or inappropriate data structures or any other design failures. It includes the ways in which it provides conceptual integrity for a system. It includes the dialog and screen designs.

Noticed that the relationship of the package is illustrated with a broken line with a transparent blocked arrow head. the subsystem stereotype is indicated (<<subsystem>>). it gives an intellectual view of how the system is structured and how its components work together. It can be deployed across a set of distributed 47
. If a package is represented as a subsystem. • It is modeled using the Package Diagram of UML. The interface can be canonical as represented by the circle as depicted by the Client Subsystem Interface. Second. Client Subsystem is dependent on the Supplier Subsystem. The deployment diagram will be used to represent this model. Some would describe it in terms of class structures and the ways in which they are grouped together. Buschmann et al. and normally. subsystems and components are distributed to the physical environment that will support the software. controls the iterative and incremental development of the software.
Describing the Package Diagram
The Package Diagram shows the breakdown of larger systems into logical groupings of smaller subsystems. Others used it to describe the overall organization of a system into subsystem. Subsystems and components are typically specified in different views to show the relevant functional and nonfunctional properties of a software system. It allows components to be developed independently as long as the interface does not change. it enables design decisions that will have a significant effect on all software engineering work products for the software's interoperability. As in the example. A package is a model element that can contain other elements. It is interpreted differently depending upon the context. Figure 4. It is a mechanism used to organize design elements and allows modularization of the software components. Packages are represented as folders.This refers to the design of the how the software will be deployed for operational use.
Software Architecture
There is no general agreed definition for the term software architecture. Lastly. It involves making decisions on how the software is built.5 defined it as follows: • A software architecture is a description of the sub-systems and components of a software system and the relationships between them. A dependency exists between two elements if changes to the definition of one element may cause changes to other elements.
Subsystems and Interfaces
A subsystem is a combination of a package (it can contain other model elements) and a class (it has behavior that interacts with other model elements). representation of software architecture enables communication between stakeholders (end-users and developers). • Defining the architecture is important for several reasons.1 shows the basic notation of the package diagram. First. • It is this definition that is being followed by this section. configured and delivered. It can be used to partition the system into parts which can be independently ordered. and the structure of the data that are used by these components. or it can be a class definition as depicted by the Supplier Subsystem Interface (stereotype is <<interface>>). Software architecture is the layered structure of software components and the manner in which these components interact. The packages are realized by interfaces. Software functionality. The dependencies are represented as broken arrow lines with the arrow head as a line. It shows groupings of classes and dependencies among them. It is the result of software design activity. The software architecture of a system is an artifact.

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. • It supports and eases maintainability. Each subsystem provides services for other subsystems. It allows the separation of the declaration of behavior from the realization of the behavior. It serves as a contract to help in the independent development of the components by the development team. another subsystem may deal with data management. • It supports portability.computational nodes and changed without breaking other parts of the system. an interface is realized by one or more subsystems. one subsystem may contain humancomputer interfaces that deals with how people interact with the system. they are known as client-server and peer-topeer communication. This is the secret of having plug-and-play components. Interfaces define a set of operations which are realized by a subsystem. and ensures that the components can work together. As an example. It typically groups together elements of the system that share common properties. The implementation of the subsystem can change without drastically changing other subsystems as long as the interface definition does not change. It encapsulates an understandable set of responsibilities in order to ensure that it has integrity and can be maintained. They are shown below.
As shown above. The specification of the interface defines the precise nature of the subsystem's interaction with the rest of the system but does not describe its internal structure. It also provides restricted security control over key resources. • It allows developers handle complexity. There are two styles of communication subsystems use. Each subsystem should have a clear boundary and fully defined interfaces with other subsystems. The advantages of defining subsystems are as follows: • It allows for the development of smaller units. • It maximizes the reusability of components.

They cannot skip layers.In a client-server communication. the client-subsystem needs to know the interface of the server subsystems. Layered architectures are commonly used for high-level structures for a system. The top layer request services from the layer below it. They. The communication is two way since either peer subsystem may request services from others. There are two approaches in dividing software into subsystems. in turn. coupling is tighter. layers request services from the layer directly below them. may use services of the next layer. In an open layered architecture. Closed layered architecture minimizes dependencies between layers 49
. In a peer-to peer communication. The client subsystem request services from the server-subsystem. In general. In this case. subsystems may request services from any layers below them. The communication is only in one direction. both approaches are used such that some subsystems are defined in layers others as partitions. not vice versa. They are known as layering and partitioning. For closed layered architecture. each subsystem knows the interface of the other subsystem. client-server communication is simpler to implement and maintain since they are less tightly coupled that the peer-to-peer communication. The general structure is depicted below:
Each layer of the architecture represents one or more subsystems which may be differentiated from one another by differing levels of abstraction or by a different focus of their functionality. Layering focuses on subsystems as represented by different levels of abstraction or layers of services while partitioning focuses on the different aspects of the functionality of the system as a whole. In practice.

There are four layer architecture. One can use the Analysis Model Validation Checklist. it is the Athlete Domain. It is designed to provide client-side and server-side support for developing distributed and multi-layered applications. 3.
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.and reduces the impact of change to the interface of any one layer. Back-end provides the enterprise information systems for data management is supported through the Enterprise Information Systems (EIS) which has a standard APIs. iterate back to the requirements engineering phase. The Presentation Layer. Partitioning is required to define these decomposed components. This section provides an overview of the J2EE Platform. validate the analysis model.
Developing the Architectural Design
In constructing the software architecture. However. 2. It consists of the following: 1. it is the Athlete Database. The relationship among them are illustrated by defining the dependencies. STEP 1: If the analysis model has not been validated yet. The J2EE platform represents a standard for implementing and deploying enterprise applications. In the example. It is particularly defined when systems are distributed. In the example. Open layered architectures allows for the development of more compact codes since services of all lower level layers can be accessed directly by any layer above them without the need for extra program codes to pass messages through each intervening layer. 2. the design elements are grouped together in packages and subsystems. This layer is responsible for the storage and retrieval of information from a repository. The Domain Layer. This layer is responsible for services or objects that are shared by different applications. it breaks encapsulation of the layers. Java 2 Enterprise Edition (J2EETM) adopts a multi-tiered approach and an associated patterns catalog has been developed. 4. This layer is responsible for executing applications that are representing business logic. This layer is responsible for presenting data to users. 3. increases the dependencies between layers and increases the difficulty caused when a layer needs to be modified. Interfaces are defined. and ensure that a class defines a single logical abstraction. Applications are configured as: 1. they are the Athlete HCI Maintenance Subsystem and the Athlete HCI Find Subsystem. The Application Layer. The Database Layer. In the example. If there are problems with the analysis model. In the example. Client-tier which provides the user interface that supports. We must ensure that attributes and responsibilities are distributed to the classes. devices or other systems. Some layers within a layered architecture may have to be decomposed because of their complexity. they are the Athlete Maintenance Subsystem and Athlete Find Subsystem. A Sample of Layered Architecture Layered architectures are used widely in practice. one or more client types both outside and inside a corporate firewall. Middle-tier modules which provide client services through web containers in the Web-tier and business logic component services through the Enterprise JavaBean (EJB) containers in the EJB-tier.

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. After making a decision on how to group the analysis classes. • Mandatory boundary classes that are not functionally related on any entity or control classes are grouped together separately. group it in a separate subsystem with the classes that collaborate to provide the said service. In this way. the package dependencies are defined. Packaging decisions are based on packaging criteria on a number of different factors which includes configuration units. • Two classes are functionally related if they interact with the same actor. packages are mechanism that allows us to group together model elements. The table below shows the visibility symbol that are placed beside the name of the class within the package. • If the boundary class is related on an optional service. allocation of resources. • If the class is removed from the package and has a great impact to a group of classes.STEP 2: Package related analysis classes together. Packaging Functionally Related Classes • If a change in one class affects a change to another class. Packaging Classes Guidelines 1. • Two class that are related to different actors should not be placed on the same package. • If no major interface changes are planned. • Two classes are functionally related if they have a relationship with one another. • Two classes are functionally related if they have a large number of messages that they can send to one another. they are functionally related. As was mentioned previously. the boundary classes should be separated from the rest of the design. and representation of the existing product and services the system uses. 2. • Optional and mandatory classes should not be placed in the same classes. Packaging Boundary Classes • If the system interfaces are likely to be changed or replaced. • A class is functionally related to the class that creates instances of it. user type groupings. when the subsystem is mapped onto an optional component interface. The following provides guidelines on how to group together classes. It defines what is and is not accessible within the package. Package Dependencies are also known as visibility. it can provide that service using the boundary class. the class is functionally related to the impacted classes. or are affected by the changes made by the same actor. the boundary classes should be placed together with the entity and control classes with which they are functionally related.

it can be refined to become: • a part of another class • an aggregate class • a group of classes that inherits from the same class • a package • a subsystem • an association or relationship between design elements The following serves as a guideline in identifying subsystems. Layers will be discussed in one of the steps. However. It is possible that analysis classes are expanded. An analysis class is a design class if it is a simple class or it represents a single logical abstraction. upgraded or replaced with alternatives. STEP 3: Identify Design Classes and Subsystems. In general. Packages should not be dependent on subsystems. or features which may be removed. 3. It should adhere to some rules. Object Collaboration. If the objects of the classes collaborate only with themselves. 1. Packages should not be cross-coupled. At this point. 4. they should be part of the subsystem. Optionality. 2. Packages in lower layers should not be dependent on packages on upper layers. 1. 2.Package Coupling defines how dependencies are defined between packages. 2. If the analysis class is complex. combined or removed from the design. decisions have to be made on the following: • Which analysis classes are really classes? Which are not? • Which analysis classes are subsystems? • Which components are existing? Which components need to be designed and implemented? The following serves as a guideline in identifying design classes. encapsulate the classes within a subsystem. and the collaboration produces an observable result. exceptions can be made and should be documented. collapsed. It the associations of the classes are optional. 1. The analysis classes are analyzed to determine if they can be design classes or subsystems. packages should not skip layers. They should be dependent on other packages or on subsystem interfaces.
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Analysis classes that provide complex services or utilities. It serves as a contract to help in the independent development of the components by the development team. control classes tend to appear in the middle and entity classes appear below. most boundary classes tend to appear at the top layer. When classes within layers are elaborated. system should support concurrency. it should be justified and documented. There are many architecture styles and patterns that are more complex and comprehensive than the simple three layer architecture. 53
. and ensures that the components can work together. the case study uses the three layer architecture. In UML. model them as different subsystems since each actor may independently change requirements. ensure that the subsystem functionality maps onto a single node. vertical subsystem is the choice. For simplicity purpose. Separating together boundary and related entity classes as one subsystem is called horizontal subsystem while grouping them together is called vertical subsystem. Defining layers of the software application is necessary to achieve an organized means of designing and developing the software. Actor. Consider visibility. no associations and the operation implementation details are not defined. 7. Volatility. If the particular functionality must reside on a particular node. types and data structures. The decision to go for horizontal or vertical subsystem depends on the coupling of the user interface and entity. no attributes. 1. they are designed based on technological requirements such as system should distributed. If dependency skips. STEP 5: Layer subsystems and classes. database access support. In general. common utilities and application specific products. it contains no internal structure. 2. and boundary classes. Substitution. no associations and only abstract operations. 5. User Interface. Normally. This type of layering is known as the three layer architecture. Existing products or external systems in the design such as communication software. It is equivalent to an abstract class that has no attributes. If two different actors use the same functionality provided by the class. Dependencies among classes and subsystem occur only within the current layer and the layer directly below it. If the boundary class is used to display entity class information. Design elements (design classes and subsystems) need to be allocated to specific layers in the architecture. Represent different service levels for a particular capability as separate subsystem each realizes the same interface. STEP 4: Define the interface of the subsystems. chances are additional layers and packages are used. Organize highly coupled classes into subsystems. system is considered a web-based application. defined and refined. 8. The following serves as a guideline in defining layers of the architecture. Distribution. Encapsulate into one subsystem all classes that may change over a period of time.3. Interfaces are group of externally visible (public) operations. 6. Interfaces define a set of operations which are realized by a subsystem. Class coupling and cohesion. 4. Separate along the lines of weak coupling. It allows the separation of the declaration of the behavior from its implementation. The possible subsystems are: 1.

Does the package description match the responsibilities?
Design Patterns
A design pattern describes a proven solution to a problems that keep recurring. Context.
Software Architecture Validation Checklist
Like any other work product. For smaller systems. Name. Are the subsystems partitioning done in a logically consistent way across the architecture? 2. are there more than seven layers? Subsystems and Interfaces 1. An application system can be customized to an organization's needs by completing the unfinished elements and adding application specific elements. It would involved specialization of classes and the implementation of some operations.2. It cannot be directly implemented. It should be detailed enough to allow the applicability of the pattern to be determined. Is the name of the interface depict the role of the subsystem within the entire system? 3. Are the name of the packages descriptive? 2. In general.
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. Layers 1. The name of the pattern should be meaningful and reflects the knowledge embodied by the pattern. The context of the pattern represents the circumstances or preconditions under which it can occur. This may be a single word or a short phrase. Patterns may be documented using one of several alternative templates. on the other hand. It is essentially a reusable mini-architecture that provides structure and behavior common to all applications of this type. the software architecture should be validated. a pattern description includes the following elements: 1. a successful implementation is an example of a design pattern. A framework can use several patterns. Design patterns are not frameworks. Frameworks are partially completed software systems that may be targeted at a specific type of application. Number of Layers. a pattern cannot incorporate a framework. and these vary in the emphasis they place on different aspects of the pattern. are there more than four layers? 2. Are all operations that the subsystem needs to perform identified? Are there any missing operations? Packages 1. Consider volatility. 2. is a solution. Design patterns. It addresses individual problems but can be combined in different ways to achieve an integrated solution for an entire system. It is a description of the way that a problem can be solved but it is not. Normally. upper layers are affected by requirements change while lower layers are affected by environment and technology change. It leverages the knowledge and insights of other developers. Small systems should have 3 – 4 layers while larger systems should have 5 – 7 layers. by itself. 3. It is more primitive than a framework. are more abstract and general than frameworks. Is the interface description concise and clear? 4. For larger systems. They are reusable solutions to common problems. The pattern template determines the style and structure of the pattern description. Use the following list questions as the checklist.

It is a description of the static and dynamic relationships among the components of the pattern. Are the consequences of using the pattern acceptable? 6. The template captures the common features. Is the context of the pattern consistent with that of the problem? 5. To get a complete overview. participants and collaboration of the pattern in detail. issues should be considered. Is there another simple solution? Patterns should not be used just for the sake of it? 4. Solution. the participants and their collaborations are all described. 6. Solution Use this pattern when a view is composed of multiple atomic sub-views. Name the pattern participants (i. This solution provides the creation of a composite view through the inclusion and substitution of modular dynamic components. Problem. background.3. Composite View Context The Composite View Pattern allows the development of the view more manageable through the creation of a template to handle common page elements for a view. Classes) that are meaningful to the application. and so forth. 3. Code or implement the operations that perform responsibilities and collaborations in the pattern.e. Problem Difficulty of modifying and managing the layout of multiple views due to duplication of code. It should provide a description of the problem that the pattern addresses. Does the pattern trigger an alternative solution that may be more acceptable? 3. All members of the development team should receive proper training. It should be view as a guide on how to find a suitable solution to a problem. Choose application specific names for the operations. A solution should resolve all the forces in the given context. It promotes reusability of atomic portions of the view by encouraging modular design. a page contains a combination of dynamic contents and static elements such header. read the pattern. 2. 5. Each component of the template may be included into the whole and the layout of the page may be managed independently of the content. Are constraints imposed by the software environment that would conflict with the use of the pattern? How do we use the pattern? The following steps provides a guideline in using a selected design pattern. Study the structure. It is important to note at this time that a pattern is not a prescriptive solution to the problem. 4. Is there a pattern that addresses a similar problem? 2. 1. Examine the sample codes to see the pattern in use. logo. It is used to generate pages containing display components that may be combined in a variety of ways. 7. footer. For a web application. The use of design patterns requires careful analysis of the problem that is to be addressed and the context in which it occurs. The structure. A solution that does not solve all the forces fails. Pages are built by formatting code directly on each view. This scenario occurs for a page that shows different 55
. Define the classes. 4. 1. It should identify and describe the objectives to be achieved within a specific context and constraining forces. The following questions provide a guideline to resolve these issues. When a designer is contemplating the use of design patterns.

When someone accesses the view directly without going through a centralized request handler. mainframe or legacy systems. This pattern has a drawback. Data Access Object Design Pattern Context The Data Access Object (DAO) Design Pattern separates resource's client interface from its data access mechanisms. Access mechanism varies based on the type of storage. A benefit of using this pattern is that interface designer can prototype the layout of the page. Front Controller Context The Front Controller Pattern provides a centralized controller for managing requests. It receives all incoming client requests. It adapts a specific data resource's access API to a generic client interface. It centralizes decision-making controls.information at the same time such as found in most website's home pages where you might find new feeds weather information. stock quotes etc. LDAP etc. When the storage type changes. handling of errors. It is used to manage the handling of services such as invoking security services for authentication and authorization. Problem The system needs a centralized access point for presentation-tier request handling to support the integration of system data retrieval. There is a runtime overhead associated with it. the actual content is substituted for these placeholders. B2B external services. view management. As the development of the project progresses. It allows maintainability of codes by separating access mechanism from the view and processing. Additionally. forwards each request to an appropriate request handler. It is a trade-off between flexibility and performance. Solution Use the Data Access Object to abstract and encapsulate all access to the data source. delegating business processing. Problem Data will be coming from different persistent storage mechanism such as relational database. we only need to change the code that specifies the access mechanism. managing the appropriate view. It implements the access mechanism required to work with the data source. Solution A controller is used as an initial point of contact for handling a request. problems may occur such as: • each view may provide its own system service which may result in duplication of code • navigation of view is responsibility of the view which may result in commingled view content and view navigation. and navigation. and presents an appropriate response to the client.
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. plugging in static content on each component. and managing the selection of content creation strategies. distributed control is more difficult to maintain since changes will often be made at different places in the software. It allows data access mechanism to change independently of the code that uses the data.

it can be clicks on buttons or menu selections. where the view registers itself with the model for change notifications or a pull model. For Web application. It divides the application into three. Model. Controller. View. It divides functionality among objects involved in maintaining and presenting data to minimize the degree of coupling between the objects. the Factory Method pattern can be used.The data source can be a relational database system. Context The application presents contents to users in numerous pages containing various data. Solution The Model-View-Controller (MVC) is a widely used design pattern for interactive applications. 3.
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. a repository similar to LDAP etc. If the underlying storage is not subject to change from one implementation to another. 1. In a stand-alone GUI client. namely. and an XMLbased Web services for suppliers. business process or changing the state of a model. so simple real-world modeling techniques apply when defining the model. The actions performed on the model can be activating device. For one application. It translates interactions with the view into actions to be performed by the model. where the view is responsible for calling the model when it needs to retrieve the most current data. It can be achieved through a push model. It represents enterprise data and the business rules that govern access to and updates to this data. • The same enterprise data needs to be updated through different interactions. external service such as B2B. Data Access Object Strategy The DAO pattern can be made highly flexible by adopting the Abstract Factory Pattern and Factory Method Pattern. • The support of multiple types of views and interactions should not impact the components that provide the core functionality of the enterprise application. 2. It renders the contents of a model. a WML from for wireless customers. it may require an HTML from for web customers. It accesses enterprise data through the model and specifies how that data is presented to the actors. a Java Swing Interface for administrators. It is responsible for maintaining the consistency in its presentation when the underlying model changes. The forces behind this pattern are as follows: • The same enterprise data needs to be accessed by different views. It serves as a software approximation of real-world process. they appear as GET and POST HTTP requests. view and controller.
Model-View-Controller Design Pattern
Problem Enterprise applications need to support multiple types of users with multiple types of interfaces. model.

called the persistent layer. We will not discuss how databases are analyzed. The techniques used here falls under the field of database analysis and design.. There are a lot of design patterns that can be use to model persistence.e. • For Centralized controller. In terms of the our software architecture.
Data Design
Data design. designed and implemented. For this course. • Duration. is a software engineering task that creates a model of the data in a more implementation specific representation. we assume that the database was implemented using a relational database system. Persistence means to make an element exists even after the application that created it terminates. we need to identify: • Granularity. It is the size of the persistent object. instead of having multiple servlets as controller. • Volume. Two persistence design patterns are discussed in the succeeding sections. 7This section discusses the concept of persistence and teaches how to model persistent classes. It defines whether more or less the object is constant. do we allow modifications or updates. It defines how the object will survive if a crash occurs. also known as data architecting. The Front-Controller pattern can be a useful pattern for this strategy. normally.
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. and Enterprise JavaBeans (EJB) components as the model. use Java Server Pages (JSP) to render the view. • Reliability. It defines how long to keep the object persistent.The strategies by which MVC can be implemented are as follows: • For Web-based clients such as browsers. is created on top of the database layer. i. our programs should be able to connect to the database server. discussed in a Database Course. It is the number of objects to keep persistent. To access the data in a database system. a main servlet is used to make control more manageable. For classes that needs to be persistent. another layer. • Access Mechanism. Servlet as the controller.

charts etc. continuous forms.
Report Design
Reports can be placed on an ordinary paper. reports and screens. screen-based or microfilm or microfiche. devices and other systems that interoperate with it. reports and screens are critical in determining how the system will be acceptable to end-users. • Screens are used for low volume output.Interface Design
The Interface Design is concern with designing elements that facilitate how software communicates with humans. • Screens are used for intermediate steps in long interactive process. Preprinted Forms. graphs. Designing good forms. The following gives the steps in designing reports. There should be a balance between the number of copies generated with the number of pages. Media • Where will the report be produced on CRT Screen. When do we use • Reports • Reports • Reports reports? are used for audit trails and controls. Microfilm or microfiche. As software engineers. pre-printed forms. Report Figures • Do the user required reports to generate tables. particularly. Number of Copies and Volume. etc. When to use Screens? • Screens are used to query a single record from a database. Bond Paper. In this section. • Forms are used if personnels need to do the transaction but does not have access to workstations. Storage media. 5. • How many copies of the report will be generated? • On the average how many pages will be generated? • Can the user do without the report? • How often to do the user file a copy? Is it really needed? 2. It will ultimately establish the success of the system. Report Design Consideration 1. Ordinary Continuous Forms. we will be concentrating on design elements that interact with people. are used if it is to voluminous for on-line browsing. Report Generation • When do users need the report? • When is the cut-off period of entering or processing of data before reports are generated? 3. are used for compliance with external agencies. Report Frequency • How often do the user need the report? 4.
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. • Forms are used if they are legally important documents. we would want to decrease emphasis on reports and forms and we want to increase emphasis on the screen.
When do we use forms? • Forms are used for turnaround documents.

preparation date. then. • It is also a good place for an indicator that nothing follows. • Summary pages can be printed at the beginning of the report or at the end. Consider the following tips in designing the report footer. Consider the following tips in designing the detail line. • Remove corporate name from internal reports for security purposes. 2. detail lines. Do not use this space. Adhere to standard printout data zones of the report layout. such as Current Sales with Year-to-end Sales or Account number. • Use only logos on all externally distributed documents. • Report heading should contain title of the report. • Group related items. • Place page totals. 4. • Clearly describe report and contents. club name and page number. • Select only one. it would be appropriate to include punctuation marks and sign. • Column headers identify the data items listed. The standards are used as guide for the implementation. footers. STEP 2: Prepare Report Layouts. • Important data are positioned on top of the document. grand totals and code-value tables in this area. • Bottom of each page provides instructions or explanation of each code while bottom last page contains grand totals and indication of no more pages to follow. The data zones are the headers. Developing the Report Layouts STEP 1: Define the Report Layout Standards. Consider the following tips in designing report headers. If more than one line is needed. • If trends are part of the report. Name and Address. • Body of report should have descriptive data on the left side and numerical data on the right side. and summary. alphanumeric fields are grouped on the first line and numeric fields are grouped in the next line. • Important fields are placed on the left side. • It is a good idea to group the number of details per page by monetary values such as by 10's. Fit details in one line. 20's and 50's. • Align column headers with data item's length. For representing data that will appear on the columns of the report use the following format conventions. • Always include report date and page numbers. 5. • Codes are always explained when used. • Avoid printing repetitive data. • Dates use MM/DD/YY format. 3. Consider the following tips in designing the summary page. • For numeric representation such as money.Report Layout Guidelines 1. • One line should represent one record of information. represent them in graphic form such as charts. • The first five lines and the last five lines are used for the headers and footers. left to right.
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They should be brief. Use positive. squared off. General instructions are placed on top. For handwritten answer spaces. The answer space should be enough for user to comfortably enter all necessary information.Forms Design
Forms are usually used for input when a workstation is not available. for small font size. Lower case print is easier to read that uppercase. Instructions should appear on the form except when the same person fills it over and over again. The following are the steps in designing forms. Use familiar words. they should not be used. 2. 6 or 8 lines per inch is a good measurement. Use upper letters to call attention to certain statements. 61
. Use the following guidelines for typefaces of the fonts. • Colors Schemes • White copies goes to the applicant. active and short sentences. If the form will be used for a typewriter. even when compressed • Capital letters are desirable for headings • Italic • Has serifs and a distinct slant • Hard to read in large amounts of long letters • Good for printing out a work or phrase • Roman • Has serifs but does not slant • Best for large quantities • Good for instructions 5. However. Avoid using "not". It is sometimes used as a turnaround document. Forms Layout Guidelines 1. • Gothic • Simple. 3 lines per inch with 5 to 8 characters per inch is a good measurement. no serifs • Easy to read. Specific instructions should be placed just before the corresponding items. • Paper size should not be bigger than 8 1/2” x 11”. "except" and "unless". An example of a standard for defining forms is listed below. 4. Developing the Form Layouts STEP 1: Define the standards to be used for designing forms. 3.

use the value 'Student ID' as the label.'. • Important data should be positioned on left side of document. Several software vendors provide style guides that you may use. 2. However. you have a data item that represents a student identification number. Redesign if necessary. • Heading should include Page Number and Title. when designing interfaces. the system will respond. 62
. particularly. Consistency helps users learn the application faster since functionality and appearance are the same across different parts of the application.sun. Using the standard format defined in step 1. Direct Manipulation Metaphor is an interaction between user and the system using graphical user interfaces (GUIs). design the layout of the forms. You may decide to use 'Student ID' as its caption. For every screen that display this item. there are two metaphors used in designing userinterface are used. layout of the screens etc. • Dates should use DD/MM/YY Format. i. Such interfaces are eventdriven. let say clicks a button (event). Dialog Metaphor is an interaction between the user and the system through the use of menus. ● They should be displayed in the same way such as in the case of presenting dates. Such metaphor is widely used in the structured approach of developing user-interfaces that are shown on character or text based terminals.. and they should be the same throughout the entire application. As an example. for the data entry screens. we use the direct manipulation metaphor. Do not change it.apple. In general. For object-oriented development which uses visual programming integrated environments. • Pink copies goes to the coach. When presenting data items to users.com) 3. STEP 2: Prepare Form Samples. It gives the user an impression that they are manipulating objects on the screen. Standardize the screen layout. another screen must appear. • Logos are only used for all externally distributed documents. 2. always remember that: ● They should have a screen label or caption. ● As much as possible. If the format of the dates follows 'MM-DD-YYYY' format. • Binding should use 3-hole paper. 1. they should be located on the same place in all screens. Dialog and Screen Design Guidelines 1. If the main idea changes. Common style guides are listed below: ● Java Look and Feel Design Guidelines (http://java. do not change it to 'Student Number' or 'Student No. This applies to commands. the format of the data as it is presented to the user such as date formats. then all dates should be displayed in this format. • Ruling should follow 3 lines per inch. when a user. Style guides support consistency of interface. Stick to the rule: ONE IDEA PER SCREEN. This would involved defining style guides that should be applied to every type of screen element.• Yellow copies goes to the club staff.e.com) ● The Windows Interface Guidelines for Software Design ● Macintosh Human Interface Guidelines (http://developer. several guidelines should be followed.
Screen and Dialog Design
The boundary classes are refined to define screens that the users will be using and the interaction (dialog) of the screens with other components of the software. function keys or entering of a command through a command line.

Vertical prototypes takes one functional subsystem of the whole system and develops it through each layer: user-interface. and to some extent. Horizontal prototypes provide a model of the user interface. Throwaway Prototypes are prototypes that are discarded later after they have served their purpose. 1. Basically. It basically models the behavior of the screen when a user does something on the screen elements such as clicking the OK Button. It also identifies the events that causes the state change. this type of prototype shows the screen sequencing when the user interacts with the software.
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. The collaboration diagrams and sequence diagrams are used in this step. 3. Use "XX% completed" messages or line indicators. For each screen class. This type of prototype is done during the requirements engineering phase. 2. The State Chart Diagram is used to model the internal behavior of the screen. NetBeans and Java Studio Enterprise 8 provides a means to visually create our prototypes. It shows how the object's state changes as a result of events that are handled by the object. This step would require us to model the screen as a class. Provide meaningful error messages and help screens. It deals only with the presentation or view layer of the software architecture. For controllers that require a longer time to process. STEP 3: For each screen class. The use of Visual Programming Environment can support the development prototypes. AVOID PROFANITY! Developing the Screen and Dialog Design STEP 1: Prototyping the User-interface. behaves like the finished product but lacking in certain features. 6. If possible. A prototype is a model that looks. it would be wise to always inform the user of the next step. 5. STEP 2: For each screen. design the screen class. No functionality is emulated. keep user informed of what is going on. It is like an architect's scale model of a new building. There are several types of prototypes.4. Describing the State Chart Diagram The State Chart Diagram shows the possible states that an object can have. we avoid creating such prototypes. some logical functionality and database. Wizard-type dialog design is always a good approach. STEP 4. As much as possible. model the behavior of the screen with other classes. The behavior of the screen class relative to the other classes is known as the dialog design. model its internal behavior.

and the action that needs to be performed when the event is triggered. 64
.The initial state. The state is represented as a rounded rectangular object with the state name inside the object. as represented by a solid filled circle. what operation should be perform upon exiting the state. and what operation should be perform while the object is in that state. signifies the entry point of the transition. States can have internal actions and activities. The final state. as represented by the bull's eye. there is an extended or enhanced notation that can be used when defining the state of a class. Internal actions of the state defines what operation should be perform upon entering the state. each state of which can be entered and exited independently of substates in the other set. The event should be an operation defined in the class. any guard conditions that needs to be evaluated during the triggering of the event. Nested states allow one to model a complex state through defining different level of detail. A transition should have a transition string that shows the event that causes the transition.
Concurrent states means that the behavior of the object can best be explained by regarding the product as two distinct set of substates. Similar with other diagrams in UML. signifies the end of the diagram. A transition is represented by an arrow line. An object cannot remain in its initial state but needs to move to a named state.

If a class is dependent on a base class. 3. Software engineers are encouraged to develop clientspecific interface rather than a single general purpose interface. its interface. It is important that all interfaces and messages that allow classes within the component to communicate and collaborate be defined. The boundary subsystems are replaced by the classes for the screens or user interfaces. STEP 6: Modify the software architecture. Identify all the attributes and operations of the screen. Classes should depend on abstraction. This minimizes inheriting irrelevant operations to the client. and communication mechanism allocated to each software component. particularly.
Component-level Design
The Component-level Design defines the data structure.
Basic Component Design Principles
Four basic principles are used for designing components. 65
. If additional control classes are defined. The software engineer should define a component such that it can be extended without the need to modify the internal structure and behavior of the component. 4. As an example. This principle enforces that any derived class should comply with any implied contract between the base class and any component that uses it. The documentation is similar to documenting DBClasses and Persistent Classes. Abstractions in the target programming language supports this principles. A component is the building block for developing computer software. It is a replaceable and almost independent part of a software that fulfills a clear function in the context of a welldefined architecture. • Implementation component name should come from the implementation specific name. In object-oriented software engineering. Liskov Substitution Principle. The Open-Close Principle. Each class in the component should be fully defined to include all attributes and operations related to the implementation. The more a component depends on other concrete components. Only operations specific to a particular client should be defined in the client-specific interface. they should be open for extension but they should not be modifiable. They are used to guide the software engineer in developing components that are more flexible and amenable to change and reduces the propagation of side effects when change do occur. add them to the architecture. As an example. the more difficult it can be extended. Dependency Principle. not on concretions. It can be independently developed. that class can use any derived class as a substitute for the base class. PCLAthlete is the persistent class list for the athletes.
Component-level Design Guidelines
This guideline is applied to the design of the component.STEP 5: Document the screen classes. a component is a set of collaborating classes that fulfills a particular functional requirement of the software. Component • Architectural component names should come from the problem domain and is easily understood by the stakeholders. interface characteristics. When defining modules or components. 1. its dependencies and inheritance. 1. The derived class or subclass can be a substitute for the base class. Interface Segregation Principle. the end-users. 2. algorithms. a component called Athlete is clear to any one reading the component.

• Use stereotypes to identity the nature of the component such as <<table>>. The classes are refined in such a way that it can be translated into a program. 3. This step involves a series of substeps.
Component Diagram
The Component Diagram is used to model software components.3: Refine attributes of each class. <<database>> or <<screen>>. AddAthleteController. Figure 4. Dependencies and Inheritance • Dependencies should be modeled from left to right.
Developing the Software Component
All classes identified so far should be elaborated including the screens. Use data types and naming conventions of the target programming language. A short description is attached to the operation. dependencies and hierarchies. Use data types and naming conventions of the target programming language. redefine the sequence and collaboration diagrams to reflect the interaction of the current classes. STEP 1.2: Distribute operations and refine operation signature of the class. STEP 1: Refine all classes. Refactoring may be required before proceeding. 2. • Component interdependence are modeled from interface to interface rather than component to component. Figure 4. • They should flow from the left-hand side of the implementing component. Developing the component-level design involves the following steps. and data design classes. their interface. Interfaces • The canonical representation of the interface is recommended when the diagram becomes complex. STEP 1. The Client Component is dependent on the Supplier Component. • Inheritance should be modeled from bottom (subclass or derived class) to top (superclass or base class). • Show only the interfaces that are relevant to the component under consideration. The dependency can be named. STEP 1. The dependency is depicted by the broken arrow.55 shows the notation of the this diagram.
Component Diagram Notation A component is represented by a rectangular box with the component symbol inside.57 shows the elaboration
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5: Document the class. Nodes would represent the computers. The components identified in the Component-level design are distributed to hardware. Define the components using the component diagram. STEP 1.of the attributes of the AddAthleteController. identify the pre-conditions and postconditions. it was decided that no repackaging is necessary. The visibility symbols are enumerated in the table below:
STEP 1. A short description is attached to the attribute. In our example. The communication associations show network connectivity. refine the packaging of the classes. STEP 3. They are represented as a threedimensional box.
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. Also. STEP 2: If necessary.
Deployment-level Design
The Deployment-level Design creates a model that shows the physical architecture of the hardware and software of the system.4: Identify visibility of the attributes and operations. It highlights the physical relationship between software and hardware. Post-conditions are the conditions that exists after the class is used. Pre-conditions are the conditions that must exists before the class can be used.
Deployment Diagram Notation
The Deployment Diagram is made up of nodes and communication associations. Define the software components. include the description of the attributes and operations. Particularly.

Are all operations and attributes within the class functionally coupled? 4.
Design Model Validation Checklist
Validation is needed to see if the design model: • fulfills the requirements of the system • is consistent with design guidelines • serves as a good basis for implementation Software Component 1. Does the class exhibit the required behavior that the system needs? Operation 1. Are the implementation specifications for an operation correct? 6. is the operation defined in the interface mapped to a model element within the software component? Class 1. Is the attribute needed or used by the class?
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. Just distribute the software components identified in the component-level design to the computer node where it will reside. Is the attribute signify a single conceptual thing? 2. Can we understand the operation? 2. Is the class signifies a single well-defined abstraction? 3. Is there any model element within the software component visible outside? 4. Are the parameters defined correctly? 5. Does the operation signature comply with the standards of the target programming language? 7. If the software component has an interface. Is the name of the attribute descriptive? 3. Is the name of the class clearly reflect its role within the system? 2. Are all specific requirements about the class addressed? 6. Is the operation signature correct? 4. Are the dependencies defined? 3. Are there any attributes.Developing the Deployment Model
Developing the deployment diagram is very simple. Is the operation needed or used by the class? Attribute 1. Is the name of the software component clearly reflect its role within the system? 2. operations or associations that needs to be generalized? 5. Does the operation provide the behavior that the class needs? 3.

This is computed as the summation of the complexity of all methods of a class. We compute for the complexity of each method and find the sum.
Design Metrics
In object-oriented software engineering. the class hierarchy.60. However. 3. Depth of the Inheritance Tree (DIT). This ensures that the model is related to a requirement. 2. There are many complexity metric that can be used but the common one is the cyclomatic complexity. 1. Weighted Methods per Class (WMC). Assume that there are n methods defined for the class. As the number of children increases.Mapping the Design Deliverables to the Requirements Traceability Matrix
Once the software components are finalized. we need to tie them up to the RTM of the project. care is given such that 69
. the NOC of Class4 is 2. Number of Children (NOC). the likely it will become more complicated. Measures and metrics for an individual class. Children of a class are the immediate subordinate of that class. This is discussed in the chapter for Software Testing. There are many sets of metrics for the object-oriented software but the widely used is the CK Metrics Suite proposed by Chidamber and Kemerer6. Consider the class hierarchy in Figure 4. the class is the fundamental unit. It is defined as the maximum length from the root superclass to the lowest subclass. reuse increases. and class collaboration is important to the software engineer especially for the assessment on the design quality. the more complex is the inheritance tree • as the number of methods grows within the class. The number of methods and their complexity indicates: • the amount of effort required to implement and test a class • the larger the number of methods. It consists of six classbased design metrics which are listed below. It also aids the software engineer in tracking the progress of the development.

methods are coupled together through this attribute. the number of testing the children of the parent class also increases. Response for a class (RFC). 4. It is the number of methods that are executed in response to a message given to an object of the class. As this number increases. It is the number of methods that access an attribute within the class. It also complicates modifications and testing. 5. It is best to keep LCOM as low as possible. Lack of Cohesion in Methods (LCOM). If this number is high.
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. Of course. Coupling Between Object Classes (CBO). the effort required to test also increases because it increases the possible test sequence. It is the number of collaboration that a class does with other object. It is for this reason that CBO is kept to a minimum. 6. the reusability factor of the class decreases. This increases the complexity of the class design. as the number of children increases.the abstraction represented by the parent class is not diluted by its children which are not appropriately members of the parent class. As this number increases.

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. it can help programmers organize their thoughts and avoid mistakes. It also gives some software engineering practices that every programmer must keep in mind. For the software. This includes the minimum and recommended requirements of the hardware and software. Standards on the source code documentation. a great deal of cooperation and coordination is required. 2. Design correspondence with source code allows us to locate the necessary source code to be modified. These may be: 1. high-cohesion and well-defined interfaces should also be the program characteristics. software integrators and software maintainers. Changes are first reflected on the design. Sometimes when writing a code. How to document the source codes to make them clear and easy to follow makes it easier for the programmer to write and maintain the codes. The design model has no value if the design's modularity is not carried forward to the implementation. the programmer must take advantage of the characteristics of the design's organization. However. and how it fits in the software to be developed. 3. It also helps in the translation from the design code to the source code through maintaining the correspondence between the design components with the implementation components. First. it will be traced down to lower level components. several people are involved. Thus. they include versions.Chapter 4 Implementation
Programs are written in accordance to what is specified in the design. It allows communication and coordination to be smooth among the software development teams.
Programming Standards and Procedures
Teams are involved in developing a software. The software's general purpose might remain the same throughout its life cycle but its characteristics and nature may change overtime as customer requirements are modified and enhancements are identified. Second. the impact should be analyzed and addressed. The people involved in the development software must decided on implementation specific standards. It is for this reason that programming standards and procedures be defined and consistently used. Design characteristics such as low coupling. A variety of tasks performed by different people is required to generate a quality product. It also helps in locating faults and aids in making changes because it gives the section where the changes are applied. This will be discussed in the programming documentation guidelines. First. Programming standards and procedures are important for several reasons. the designer of the system might not able to address the specifics of the platform and programming environment. Third. it can assists other team members such as software testers. It is important that others be able to understand the code that was written. This chapter does not intend to each programming as this is reserved for a programming course. This chapter gives some programming guidelines that may be adopted when creating codes. Platform where the software will be developed and used. Translating design can be a daunting task. why it was written. Standards for correspondence between design and source codes. However. codes should be written in a way that is understandable not only to the programmer who did it but by others (other programmers and testers). Second. if upgrades are necessary. Upgrades are not really recommended. the data's structure and programming language constructs while still creating code that is easily maintainable and reusable.

Programming Guidelines
Programming is a creative skill. this information is placed at the beginning of the code.
Using Pseudocodes
The design usually provides a framework for each component. Two program documentation are created: internal documentation and external documentation. Pseudocodes can be used to adapt the design to the chosen programming language. system states and changes in the variables. Modularity is a good design characteristic that must be translated to program characteristic. and so on. This section discusses several guidelines that apply to programming in general. one can add history of revisions that was done to the component. He has the flexibility to choose the particular programming language constructs to use. how to use them. They are structured English that describes the flow of a program code. Normally. By adopting the constructs and data representations without becoming involved immediately in the specifics of a command or statement. This section of the source code is known as the header comment block. algorithm and control flow Optionally. The history element consists of: • Who modified the component? • When the component was modified? • What was the modification?
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Control Structure Guidelines
The control structure is defined by the software architecture. algorithms. Codes can be rearranged or reconstructed with a minimum of rewriting. Coupling and cohesion are another design characteristics that must be translated into program characteristics. It acts as an introduction to the source code. and control flow.
Documentation Guidelines
Program Documentation is a set of written description that explain to the reader what the programs do and how they do it. The design component is used as a guide to the function and purpose of the component. It is an outline of what is to be done in a component. It is important for the program structure to reflect the design's control structure. a programmer can hide implementation details at different levels. Internal Documentation It is a descriptive document directly written within the source code. test and maintain. By building the program in modular blocks. how the data will be represented. A summary information is provided to describe its data structures. The programmer has the flexibility to implement the code. It is directed at some who will be reading the source code. It identifies the following elements: • Component Name • Author of the Component • Date the Component was last created or modified • Place where the component fits in the general system • Details of the component's data structure. it is based on messages being sent among objects of classes. making the entire system easier to understand. In object-oriented software. The programmer adds his creativity and expertise to build the lines of code that implement the design. the programmer can experiment and decide which implementation is best.

This section serves as a review of abstract classes and interfaces. For objectoriented system. To reuse the class. the compiler creates them. 4.500 format for distinguished names. When a Java file containing a package statement is compiled. it is: package abl. Avoid using GOTO's. They are actually directories used to organize classes and interfaces. one may need to restructure the program. The following are the steps in defining a package in Java. Java provides a convention for unique package and class names. 2. In the example.Internal documents are created for people who will be reading the code. It also allows software to 73
. Use meaningful variable names and method names. the athlete. 6. The Java Programming Language provides a mechanism for defining packages. One of the goals of programmers is to create reusable software components so that codes are not repeatedly written. the result *. it identifies the pre-conditions and post-conditions of the source code. External Documentation All other documents that are not part of the source code but is related to the source code are known as external documents. A good programming practice is using abstract classes and interfaces. Choose a package name. 3. Avoid writing codes that jump wildly from one place to another. They describe how components interact with one another which include object classes and their inheritance hierarchy.pc. It should follow the Internet Domain Name Convention as specified in X. one starts with a draft.athlete. If these directories do not exist. Consider the code of the Athlete persistent class shown in Text.class file is placed under the pc directory under the athlete which is under the abl directory. 4.pc which is the name of the package for persistent classes and class lists.class file is placed in the directory specified by the package statement. These type of documents are indented for people who may not necessarily read the codes. Add the package statement to the source code file for a reusable class definition. just import the package.athlete. The compiled class is made available to the compiler and interpreter. Writing code is also iterative. Tips in writing codes 1.
Implementing Controllers
Implementing controllers is similar to writing programs in your previous courses. 1. the package name is abl. The use of abstract classes and interfaces greatly increase the ability of the software to be reusable and manageable. Have separate methods for input and output. Use formatting to enhance readability of the codes such as indention and proper blocking. Place additional comments to enlighten readers on some program statements. the name one uses for his classes may conflict with classes developed by other programmers.. Compile the class so that it is placed in the appropriate package directory structure. If the control flow is complex and difficult to understand. 3. If the class is not public. Placing a package statement at the beginning of the source file indicates that the class defined in the file is part of the specified package.e. 2.
Implementing Packages
Packages provide a mechanism for software reuse. 5. Package names should be in all-lowercase ASCII letters. it can be used only by other classes in the same package. Define a public class. In this example. In the example. With hundreds of thousands Java programmers around the world. i.

Through interfaces. to implement common behaviors. they are defined independently. both of the classes have some similar methods which compares them from other objects of the same type. This section serves as a review of abstract classes and interfaces in Java7. Interfaces define the signatures of a set of methods without the body. An abstract class is a class that cannot be instantiated. This means that an interface can be used in places where a class can be used. To create an abstract method. Interfaces define a standard and public way of specifying the behavior of classes. As we can see here.
Interfaces
An interface is a special kind of block containing method signatures (and possibly constants) only. just write the method declaration without the body and use the abstract keyword. we can actually capture similarities among unrelated classes without artificially forcing a class relationship. since program may call an interface method and the proper version of that method will be executed depending on the type of object passed to the interface method call. Let's take as an example a class Line which contains methods that computes the length of the line and compares a Line object to objects of the same class. Those methods in the abstract classes that do not have implementation are called abstract methods.
Inheritance among Interfaces
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. They allow classes.have a 'plug-and-play' capabilities. defining the broad types of actions possible with objects of all subclasses of the class. suppose we have another class MyInteger which contains methods that compares a MyInteger object to objects of the same class.
Abstract Classes
Now suppose we want to create a superclass wherein it has certain methods in it that contains some implementation. Another common characteristic is that both interface and class can define methods. However. an interface does not have an implementation code while the class have one. Note that interfaces exhibit polymorphism as well. let's say interface Relation which has some comparison method declarations. and some methods wherein we just want to be overridden by its subclasses.
Why do we use Interfaces?
We need to use interfaces if we want unrelated classes to implement similar methods. but they are not related whatsoever. We can create an interface class. an interface can only define constants and an interface have no direct inherited relationship with any particular class.
Interface vs. regardless of their location in the class hierarchy. In order to enforce a way to make sure that these two classes implement some methods with similar signatures. Abstract Class
The following are the main differences between an interface and an abstract class: interface methods have no body. we can use an interface for this.
Interface vs. It often appears at the top of an object-oriented programming class hierarchy. Class
One common characteristic of an interface and class is that they are both types. Now.

Thru interfaces. This is the number of statement lines that was used. Cost.Interfaces are not part of the class hierarchy. We can use the RTM to determine how many of the classes have been implemented. Why do we use Interfaces? We need to use interfaces if we want unrelated classes to implement similar methods. Classes. Another reason for using an object's programming interface is to reveal an object's programming interface without revealing its class. unrelated to implementation. They serve as history data that can be used for estimation for other projects. 3. It is a special kind of block containing method signatures (and possibly constants) only. to implement common behaviors. regardless of their location in the class hierarchy. Interfaces define a standard and public way of specifying the behavior of classes. It defines polymorphism in a declarative way. we can actually use an interface as data type. One common characteristic of an interface and class is that they are both types. They allow classes. but present in other object-oriented languages like C++. integrated and tested. The total number of documentation produced. They should be entered in this column under the appropriate package. Effort. This is the total number of classes created. since program may call an interface method and the proper version of that method will be executed depending on the type of object passed to the interface method call. Interfaces define the signatures of a set of methods without the body.
Implementation Metrics
Since the program characteristics must correspond to design characteristics. 5. It can be for a program. additional classes may have been developed. As we can see later on the section Interface vs. 75
. interfaces can have inheritance relationship among themselves. Number of Classes. 1. This is the total number of days or months the project was developed. This means that an interface can be used in places where a class can be used. Note that interfaces exhibit polymorphism as well. It is basically used later on in managing similar projects. This is the key to the "plug-and-play" ability of an architecture. Multiple inheritance is not present in Java. 2. we need to use interfaces to model multiple inheritance which allows a class to have more than one superclass. Rather. no additional RTM elements are used for the implementation phase. The interface methods have no body. we can actually capture similarities among unrelated classes without artificially forcing a class relationship. However. they are defined independently. Other metrics considered at implementation phase are used for succeeding similar projects. An interface formalizes polymorphism. the metrics used for implementation are the metrics for the design. component or entire software. during the course of the development.
Mapping Implementation Traceability Matrix
Deliverables
with
the
Requirements
Normally. an interface can only define constants and an interface have no direct inherited relationship with any particular class. However. Lines of Code (LOC). The total cost of developing the software. we monitor the development of each software component defined under the Classes column. 4. Number of Documentation Pages. Finally.

Fault Correction and Removal is the process of making changes to the software and system to remove the fault. Software testing encompasses a set of activities with the primary goal of discovering faults and defects. 6. They ask the software developers to correct any errors that they have discovered. Testing should begin “in small” and progress toward testing “in the large”.Chapter 5 Software Testing
Software is tested to detect defects or faults before they are given to the end-users. software developers and quality assurance group conduct software testing. it has the following objectives: • To design a test case with high probability of finding as-yet undiscovered bugs • To execute the program with the intent of finding bugs Software Testing Principles 1.
Introduction to Software Testing
Software is tested to demonstrate the existence of a fault or defect because the goal of software testing is to discover them. Software testing is performed by a variety of people. To be most effective. Exhaustive testing is not possible but there are testing strategies that allow us to have good chance of constructing software that is less likely to fail. It is a known fact that it is very difficult to correct a fault once the software is in use. The Pareto Principle states that 80% of all errors uncovered during testing will likely be traceable to 20% of all program modules or classes. Their main goal is to uncover as many errors as possible. All tests should be traceable to the requirements. Test should be planned long before testing begins. building block of software is the class. The Pareto Principle applies to software testing. an independent third party (normally. 3. Software testing begins from a single component using white-box and black-box techniques to derive test cases. they may have vested interest of demonstrating that the code is error-free. There may be instances that a subset of 76
. It has goals of ensuring that the software constructed implements a specific function (verification). 4. Software developers are responsible for testing individual program units before they perform the integration of these program units. The Quality Assurance group may be tasked to perform the test. Software testing strategies are also presented to help us understand the steps needed to plan a series of steps that will result in the successful construction of the software. However. Fault Identification is the process of identifying the cause of failure. 5. In a sense. 2. a software testing group) should conduct the test. Specifically. integration of the class through communication and collaboration with other tested classes is tested. In this chapter. Software Testing Strategies integrate software test case design methods into a wellplanned series of steps that result in the successful implementation of the software. they may be several. It is a road map that helps the end-users. Once the class is tested. For object-oriented software development. and that the software is constructed traceable to a customer requirements (validation). a test is successful only when a fault is detected or is a result of the failure of the testing procedure. the methods and techniques to develop test cases will be discussed.

This complexity measure is used as a guide for defining a basis set of execution paths to be tested. • Tests all loops at their boundaries and within their operational bounds. normally. • Tests paths within the components that are considered “out of the mainstream”. Its goal is to ensure that internal operations perform according to specification of the software component. Basic Path Testing Basis Path Testing is a white-box testing technique that enables the test case designer to derive a logical complexity measure based on the procedural specification of a software component. know how the software works and tests if it conforms to the specified functionality in the requirements. and define a set of project milestones. In order to have an organized way of testing the software. by the leader of the quality assurance group. the operation or method procedural design will be used. It ensures that no logical errors. A Test Specification is an overall strategy that defines the specific tests that should be conducted. It checks if internal operations perform as specified. It is a test case design technique that uses the internal control structure of the software component as defined by their methods to derive test cases. It also includes the procedures on how to conduct the test.
Software Test Case Design Methods
There are two ways software is tested. They are discussed in the succeeding section. For classes. and all internal components have been adequately tested. a test specification needs to be developed. Use a procedural specification as input in deriving the basic set of execution path. The other approach is to test the software as a whole. Steps in Deriving Test Cases using Basis Path Testing STEP 1. assume that the following is pseudo-code of some method of some class. i.
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. There are several techniques that can be employed in defining test cases using the whitebox approach..a test will be performed again to ensure that corrects of the fault does not generate additional or new errors. The first approach is known as white-box testing while the second approach is known as black-box testing. Finally.
White-Box Testing Techniques
White-Box Testing is also known as glass-box testing. One approach is to test the internal workings of the software. If there is no quality assurance group. • Tests all logical decisions on their true or false sides. It can be used to track the progress of the development team. the software is tested as a whole system.e. and • Tests internal data structures for their validity. incorrect assumptions and typographical errors have been missed. It produces test cases that: • Ensures that all independent paths with the component have been tested at least onces. the project leader should formulate one. The procedural specification can be the design (pseudo-code or flowchart) or the source code itself. As an example.

The cyclomatic complexity is used to determine the complexity of the procedural code.1 shows the flow graph of the sample procedural code. It can be mapped to sequences or conditions. edges and regions. which is the basis of the basic set. Figure 6. It uses nodes. They represent flow of control similar to flow charts. The graph does not normally shows the code. Draw the flow graph of the procedural specification. 1. The number of regions of the flow graph. It can be computed in three ways.
STEP 3. Areas that are bounded by the edges and nodes are called regions. It is a number that specifies the independent paths in the code. The edges are the links of the nodes. It is placed there for clarification purposes. The flow graph depicts the logical control flow of the procedural specification. 78
. The nodes represent one or more statements.STEP 2. Compute for the complexity of the code.

looping testing and data flow testing. • Skip the loop entirely. There are four classes of iteration: simple. n + 1 passes through the loop 80
. Control Structure Testing Control Structure Testing is a white-box testing technique that test three types of program control. It is a test case design method that test the logical conditions contained in a procedural specification. It is a test case design method that focuses exclusively on the validity of iterative constructs or repetition. condition testing. Looping Testing. n. 1.) For Node-3. As an example. consider the following condition of a program. concatenated. • m passes through the loop where m < n • n – 1. evaluation of var1 should lead to Node-4 (Identify value of var1) Expected Results: should produce necessary result for Node-9.
2. It focuses on testing each condition in the program by providing possible combination of values. if ((result < 0) && (numberOfTest != 100)) The test cases that can be generated is shown in the table below. the test cases can be derived from the following possible execution of the iteration or repetition. namely.PATH 1 Test Case: For Node-1. They are shown in the table below. Condition Testing.
For Simple Iteration. • Only one pass through the loop. • Two passes through the loop. condition2 should evaluate to TRUE (Identify the necessary values. nested and unstructured.

create a graph of software objects. It defines a set of test cases that finds incorrect or missing functions. Software engineers derive sets of input conditions that will fully test all functional requirements of the software. the test for simple loops can be used. errors in external database access. and errors in initialization and termination. The derived test cases are: Test Case 1: • FindAthleteUI class sends a request to retrieve a list of athlete based on a search criteria. It is a test case design method that selects test paths of a program according to the locations of the definitions and uses of variables in the program. Developing Test Cases Using Graph-based Testing STEP 1.range or excluded values.For Nested Iterations. the collaboration diagram is a good input for the graph based testing because you don’t need to create a graph. • Conduct simple loop tests for the innermost loop while holding the outer loop at their minimum iteration parameter values. Traverse the graph to define test cases. the test cases can be derived from the following possible execution of the iteration or repetition. no test cases can be derived since it would be best to redesign the loop since it is not a good iteration or repetition constructs. Using nodes and edges. performance errors. errors in interface. • Work outward. • If loops are dependent. Nodes represent the software objects. • Continue until all loops have been tested. but keeping all other outer loops at minimum values and other nested loops to “typical” values. 3.
Black-Box Testing Techniques
Black-box testing is a test design technique that focuses on testing the functional aspect of the software whether it complies with functional requirements. Add other test for outof. STEP 2. Graph-based Testing Graph-based Testing is a black-box testing technique that uses objects that are modeled in software and the relationships among these objects. the test for nested loops can be used. conducting tests for the next loop. Understanding the dynamics on how these objects communicate and collaborate with one another can derive test cases. Properties can be used to describe the nodes and edges. the test cases can be derived from the following possible execution of the iteration or repetition • If loops are independent. The request is sent to the FindAthleteRecord. Create a graph of software objects and identify the relationship of these objects. Data Flow Testing. For object oriented software engineering. • Start with the innermost loop. errors in data structure. For Concatenated Iteration. For Unstructured Iteration.
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2. Input Condition is specified as a range of value. It populates the PCLAthlete class with the athlete information. Derive test cases and ensure that there is node and edge coverage. It returns the reference of the PCLAthlete to the AthleteListUI. Thus. As an example. Input condition is Boolean. reduces the effort in testing the software. Guidelines in Identifying Equivalence Classes 1. The test case is one valid input. • The AthleteListUI lists the names of the athletes. There should be an entry and exit nodes. consider a text message code of registering a mobile number to a text service of getting traffic reports. • The DBAthele request the database server to execute the SELECT statement. 4. It makes use of equivalence classes. The test case is one valid. It divides the input domain into sets of data from which test cases can be derived. 3. Derived test cases are used to uncover errors that reflect a class of errors. Input condition specifies a member of a set. which are sets of valid and invalid states that an input may be in. and two invalid equivalence classes. Guidelines for Graph-based Testing 1. Equivalence Testing Equivalence Testing is a black-box testing technique that uses the input domain of the program.• The FindAthleteRecord sends a message to the DBAthlete to process the search criteria. Input Condition requires a specific value. 2. and two invalid equivalence classes. Specify the properties. and one invalid. Establish their relationship through the use of edges. The test case is one valid and one invalid. 3. Assume that the message requires the following structure:
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. The test case is one valid. Name nodes and specify their properties. 4. Identify the start and stop points of the graph.

the test cases that can be derived: • use values n and m • just above n and m • just below n and m 2. queries of states of the component being tested and prints verification of entry. To test the module. The environment to which unit tests can be performed is shown in Figure 6. If the driver and stub require a lot of effort to develop. local data structures. and prints relevant results.4.Boundary Value Testing Boundary Value Testing is a black-box testing technique that uses the boundaries of the input domain to derive test cases. one needs to understand the behavior of the unit of software that one is testing. independent paths and error handling paths.
To create effective unit tests.
Testing your Programs
Software testing can be done in several tasks or phases. If input condition specifies number of values. Most errors occur at the boundary of the valid input values. If input condition specifies range bounded by n and m. Program testing is concerned with testing individual programs (unit testing) and their relationship with one another (integration testing). the test cases that can be derived: • use the minimum • use the maximum • just above and below minimum • just above and below maximum. It has an intention to test the smaller building blocks of a program. unit testing may be delayed until integration testing. It is the process of executing each module to confirm that each performs its assigned function. It involves testing the interface. passes data to the component to be tested. This is usually done by decomposing the software 83
. a driver and stub is used. Guidelines in Deriving Test Cases Using Boundary Value Testing 1. boundary conditions. Unit Testing Unit testing is the basic level of testing. A Driver is a program that accepts test case data. A Stub is program that performs support activities such as data manipulation. This section discusses concepts and methods that allows one to test programs.

All possible threads should be tested. Traditional way of integration testing (top-down and bottom-up strategies) has little meaning in such software. In object-oriented software engineering.requirements into simple testable behaviors. The context in which the method is used varies depending on what subclass executes it. it is necessary to re-test the software components. It should be tested in the context to which objects of the class are instantiated. Regression testing is re-execution of some subset of tests to ensure that changes have not produced unintended side effects. As the number of subclasses is defined for a base class. As an example. The sequence diagrams and collaboration diagrams can be used as the basis for this test. Thread-based Testing Approach Integration Testing is based on a group of classes that collaborate or interact when one input needs to be processed or one event has been trigger. Therefore. software component that has been changed and software components are likely to be affected by the change. Integration testing verifies that each component performs correctly within collaboration and that each interface is correct. A thread is a path of communication among classes that needs to process a single input or respond to an event. it is necessary to test draw() method in all subclasses that uses it. Re-testing occurs for the software function that was affected. it is being executed together with the private attributes and other methods within the context of the subclass. When a subclass uses the draw() method. However.e. It is important that software requirements can be translated into tests. Integration Testing After unit testing. the concept of encapsulation is used to define a class. Regression Testing Sometimes when errors are corrected. the more testing is required for the base class. there are two approaches that can be employed in performing integration testing. Object-oriented software does not have an obvious hierarchy of control structure which a characteristic of conventional way of developing software.
The draw() method is defined in Shape class. the data (attributes) and functions (methods or operation) are grouped together in a class. i. all classes must be tested for integration.
Test-driven Development Methodology
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. As opposed to conventional way of testing. operations defined in class cannot be tested separately. consider the class diagram shown below.. The smallest testable units are the operations defined in the class. All subclasses of this base class inherit this operation.

Using these two sources of 85
. Each of these pass/fail criteria adds to the knowledge of how the software must behave. Two basic steps are involved in this approach: • Write just enough test to describe the next increment of behavior. Developers are more focused because the only thing that they need to worry about is passing the next test. But. The unit tests provide a list of requirements while the source code provides the implementation of the requirements. 2. Some of them are enumerated below. • Write just enough production code to pass the test. As more unit tests are added because of new features or correction. The first iteration of the software is very simple and may not have much functionality. The other benefit of constant regression testing is that you always have a fully working system at every iteration of the development. The test-first approach is a programming technique. It centralizes knowledge. As the name implies. One of the immediate benefits of TDD is that one has a working software system almost immediately. In test-driven development. Most developers refactor code on a regular basis using common sense. and moves on. The unit tests serve as a repository that provides information about the design decisions that went into the design of the module. gets it to work. Test allows us to uncover design problems. involving analysis. Benefits of Test-driven Development There are many benefits. 6. coding and testing all together. This is why regression testing is needed. The domino effect is very prevalent in software development. Refactoring. This is less risky compared from building the whole system and hope that the pieces will work together. It is a systematic way of improving the design of the code by removing redundant or duplicate codes. 3. The unit tests serve as a common language that can be used to communicate the exact behavior of a software component without ambiguities. Writing unit tests before writing the code helps the developer focus on understanding the required behavior of the software. It allows simple incremental development. This allows you to stop the development at any time and quickly respond to any changes in the requirements. means improving the design of the existing code. This means that any change to the code that has an undesired sideeffect will be detected immediately and be corrected. A change to one module may have unforeseen consequences throughout the rest of the project. design. It provides constant regression testing. It involves a simpler development process. one writes the test first. 4. Often. the set of unit tests becomes a representative of a set of required behaviors of the software. on the other hand. TDD runs the full set of unit tests every time a change is made. each new test provides feedback into the design process which helps in driving design decisions. As a developer is writing unit test he is adding pass/fail criteria for the behavior of the software. He focuses his attention on a small piece of software.test
Test-driven Development (TDD) is a method of developing software that adopts a -first approach plus refactoring. It improves communication. one doesn't realize a design has problems until it has been used. 1. 5. It is a process of changing code so that the internal structure of the code is improved without changing the behavior of the program. the functionality will improve as the development continues. It is cleaning up bad code. It improves understanding of required software behavior.

After integration testing. take a step back and refactor the codes to remove any duplication or any other problem that was introduced to get the test running. After making some assumptions like athletes will be identified by their ids and games by dates.
2. Write a test that defines how the software should behave. Do not be afraid to refactor your code. • There must be a way to input the data needed to calculate the shooting average. Make the test run as easily and quickly as possible. stress testing which test the software under abnormal quantity. In the case of the example. 7. Test-driven development basically is composed of the following steps: 1. You don't need to be concerned about the design of the source code. Once the unit test is written. "The software must be able to compute the shooting average of every athlete by game and for the season. just get it to work. Clean up the code. To derive system test cases. the source code we are referring to is the class AthleteStatistics which contains the methods that compute the shooting average of an athlete by game and season. it is executed to verify for execution failure. recovery testing which test the recovery mechanism of the software when it fails etc. requests or processes. frequency and volume of data. 3. security testing which test the protective mechanism of the software. Now that the code is working correctly. As developers. The code fails because the code to implement the behavior has not yet been written but this is an important step because this will verify that unit test is working correctly. sequence diagrams and collaboration diagrams. If you break your code. In the context of object-oriented software engineering. Once the unit test has been verified. • There must be a way to get a athlete's shooting average for a game. you know that the first pass at writing a piece of code is usually not the best implementation. As an example. • There must be a way to get a athlete's shooting average for the entire season. you could write the test case. the code to implement the behavior is written and the unit test is run against it to make sure that the software works as expected. This may include any tests such as performance testing which test the response time and resource utilization. The software under test is compared with its intended functional specification. Requiring the developer to write the unit tests for the module before the code helps them define the behavior of the software better and helps them to think about the software from a users point of view.Test-driven Development Steps
information makes it a lot easier for developers to understand the module and make changes that won't introduce bugs. test requirements are derived from the analysis artifacts or work products that use UML such as the class diagrams. the unit test will let you know immediately. suppose that "Ang Bulilit Liga" has the following requirements. the system is tested as a whole for functionality and fitness of use. • There must be a way to identify the game. It improves software design." There are a number of behaviors the software needs to have in order to implement this requirement such as: • The software should identify an athlete.
Testing the System
System testing is concerned with testing an entire system based on its specification. the use case 86
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0 and its sub. However. STEP 2: For each use case. create a sufficient set of scenarios. Generating System Test Cases STEP 1: Using the RTM. For each use case starting from higher to lower priority. In this case. When planning test cases. The succeeding section gives the steps in deriving the test cases using use cases. they also have sequential dependencies which came from the logic of the business process the system supports. They not only have the extend and include dependencies.use cases first rather than the rest. preconditions and postconditions can be very helpful in the later stages of test 87
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Consider the RTM formulated during the analysis as shown in Table 28. functionality can be viewed as a set of processes that run horizontally through the system. The alternative flows cover the behavior of an optional or exceptional character relative to normal behavior. Users may decide to do Use Case 1. The basic flow covers the normal flow of the use case. create use case scenarios. we need to identify possible execution sequences as they may trigger different failures. prioritize use cases. prioritizing which system function should be developed and tested first is very crucial. Importance is gauged based on the frequency with which each function of the system is used. This transition from a functional to an object point of-view is accomplished with use cases and scenarios. however. Many software project development may be constrained to deliver the software soon with a relatively small team of developers. Each use case would have a basic flow and alternative flow. It is adapted from Heumann9. A scenario is an instance of a use case. or a complete path through the use case. Having a detailed description of each scenario such as the inputs. Conceptually. The RTM is a good tool in determining which system functions are developed and tested first. Each functionality does not use every object. and the objects as sub-system components that stand vertically. They represent a high level of functionalities provided by the system to the user. use cases are not independent.diagram is a good source. each object may be used by many functional requirements. End users of the completed system can go down many paths as they execute the functionality specified in the use case.

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. consider the list of scenarios for adding an athlete to the system in the table below. I indicates invalid and N/A indicates not applicable. consider the matrix as shown in the table below. Once all test have been identified they should be completed.
The test matrix represents a framework of testing without involving any specific data values. take at least one test case and identify the conditions that will make it execute. As an example. Table 31 shows sample values. The V indicates valid. The list of scenario should include the basic flow and at least one alternative flow. and validated to ensure accuracy and identify redundant or missing test cases. A matrix format is suitable for clearly documenting the test cases for each scenario. determine the data values.generation. As an example. reviewed. STEP 4: For each test case. If this is ensured then the next step is to plug in the data values for each V's and I's. The more alternative flows mean more comprehensive modeling and consequently more thorough testing. it should be tested using real data to see if some other issues like performance prop up.
STEP 3: For each scenario. The preconditions and flow of events of each scenario can be examined to identify the input variables and the constraints that bring the system to a specific state as represented by the post conditions. Before deploying the application. This matrix is an intermediate step and provides a good way to document the conditions that are being tested.

If the software exhibits these visible attributes. The following list the recommended elements for software testing in the RTM. It can range from informal test drive to planned and systematically executed tests. assure that each test is traced to a requirement. They report them to the developer for fixes. the test specification and test cases must be developed. on the other hand. End-users are asked to use the system as if it is being used naturally while the developers are recording errors and usage problems. It focuses on user-visible actions and user-recognizable output. then. It consists of a series of black-box tests cases that demonstrate conformity with the requirements. Alpha testing is conducted at a controlled environment. at the developer’s site. It is the basis for validation testing. the software complies with the requirements. Additional RTM components are added.
Mapping the Software Testing Deliverable to the RTM
Once a component is implemented. end-users are the ones recording all errors and usage problems. is conducted at one or more customer sites and developers are not present. normally.
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. A Validation Criteria is a document containing all user-visible attributes of the software. Beta testing.Validation testing starts after the culmination of system testing. At this time. We need to keep track of it. Alpha & Beta Testing Alpha & Beta Testing is a series of acceptance tests to enable customer or end-user to validate all requirements. The software is completely packaged as a system and that interface errors among software components have been uncovered and corrected. This test allows end-users to uncover errors and defects that only them can find. and at the same time.

other metrics can be considered for encapsulation and inheritance. 2. Public Access To Data Members (PAD). If the value of PAD is high. This is a measure of the number of classes or methods that an access another class’s attributes. If the value of LCOM is high. This is a measure of the percentage of class attributes that are public or protected. Lack of Cohesion in Methods (LCOM). it could lead to many side effects. Percent Public and Protected (PAP). 4. Example of such metrics are listed below. Number of Root Classes (NOR). 3.These components should be related to a software component defined in the RTM. If the value of PAP is high. 5. it increases the likelihood of side effects among classes because it leads to high coupling. As the number of root classes increases.
Test Metrics
The metrics used for object-oriented design quality mentioned in Design Engineering can also provide an indication of the amount of testing effort is need to test object-oriented software. the more states of the class needs to be tested.
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. 1. testing effort also increases. Additionally. Superclass methods should be re-tested for every subclass. Number of Children (NOC) and Depth of the Inheritance Tree (DIT).

lack of coordination. allocating. Problem Definition It is a task where the purpose of the project is clarified.Chapter 6 Introduction to Software Project Management
Building a computer software include a variety of phases. Some of these activities are done iteratively in order for the computer software be completed and delivered to the end-users for their operation.
It consists of eight (8) tasks. However. Problem Identification It is a task where a proposed project is identified. implementation of a new process or an improvement of existing facilities. The proposed project may be a new product. poor scheduling. The project plan outlines a series of actions or steps needed to develop a work product or accomplish a 91
. end-users and developers need estimates on how long the project will proceed and how much it will cost. The mission statement of the software project is the main output of this task. before the development can proceed. It is not the intention of this chapter to give a full-blown discussion of software project management. That is reserved for a Software Project Management Course. and timing resources to develop computer software that meets requirements. defined and justified. The discussion in this chapter would revolve around project management concepts that will help the group manage class-based software development projects. It should specify how project management may be used to avoid missed deadlines. Project Planning It is a task that defines the project plan. It is a systematic integration of technical. activities and tasks. inadequate resource allocation. The figure below shows the project management process. poor quality and conflicting priorities.
Software Project Management
Software project management is defined as the process of managing. human and financial resources to achieve software development goals and objectives done in an efficient and expedient manner.

technical feasibility.goal. Gantt Charts). Project Scheduling It is the task of allocating resources so that overall project objectives are achieved within a reasonable time span. Identify alternative approaches to meet the need. and the measuring approaches should be clearly specified during planning activity. reallocation of resources or expedition of task performance. The main work product is the project proposal. It involves the process of measuring the relationship between planned performance and actual performance with respect to project objectives. 3. market research. planning and design. Define the need. and new technologies. Resource Allocation It is the task of allocating resources such as money. Reporting and Controlling It is a task that involves checking whether or not project results conform to project plans and performance specification. Controlling involves identifying and implementing proper actions to correct unacceptable deviations from expected performance. initial project boundaries and scope. Common components of the project plan include project objectives. 1. to the project in order to achieve software goals and objectives. Project Termination It is that task that involves submission of final report. CPM. It should address background information. 2. people. tools. It involves the assignment of time periods to specific tasks within the work schedule. equipment. cost and benefit. It is necessary that clear expectations for each personnel and how their job functions contribute in the overall goals of the project is identified. the power-on of new equipment. material. project definition. the measurement scales. team organization and performance criteria or validation criteria. It uses techniques such as resource availability analysis (human. skills etc. or the signing of a release order. It typically comes from a variety of sources such as client or user requirements and organization engineering. Project Organization It is a task that specifies how to integrate the functions of the personnel in a project. 92
. and risk. The purpose of this task is to make informed decisions when approving.
Problem Identification and Definition
The development of a project starts with its initiation and definition. Creating a project proposal requires a series of steps. money) and scheduling techniques (PERT. Tracking. Recommend at least two alternatives. The variables to be measured. It may trigger follow-ups or spin-off projects. information. regulatory or legal requirements. facilities. It requires the skill of directing. It requires that a product study request and proposal be given to provide a clear picture of the proposed project and the rationale behind it. Corrective action may be rescheduling. rejecting and prioritizing projects. It specifies how to initiate a project and execute its objectives. It does not include details of the requirements. guiding and supervising the project personnel. It is usually done concurrently with project planning.

When defining objectives.Schedule V. what is the business opportunity or need. Business and Information System Objectives It provides specific targets and defines measurable results.Alternatives IV. Measurements and results are in terms of time.Business and Information System Objectives i.Recommendation Executive Summary It provides an introduction to the project which includes background information leading to the project’s initiation and summary of work to be performed.Costs VI. Business Objective a)Primary Objective b)Secondary Objective ii. I. who is the client. Scope It defines the boundaries of the project.Benefits VII.Risk VIII. what will not be included in the project. and what is the pertinent background information. and who requested the project development effort. It answers the questions what is the ultimate achievement expected from this proposal. cost and performance.Success Criteria III. tactical or operational objectives are supported by this project. Information System Objectives a)Primary Objective b)Secondary Objective II. measurable. It should include expertise from the following functional area: • Software/Hardware • Network Support • Data Processing Centers • Data Security • Database Administration • Clients and Users • Internal and External Auditors • Other affective or support groups All of the project proposal deliverables should be documented in the development plan or project file.Scope of the Project B. Executive Summary A. SMART (specific. result-oriented and timeoriented) and M&M’s (measurable and manageable) principles are used. It describes the functions and process that are involved in the project. attainable. It answers the questions why is the project important. It answers the following question: what are the desired results or benefits of this project.4. The project proposal outline can be seen below.
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. what will be included in the project. and what strategic. Obtain approval A proposal team can be established to do the project proposal.

what are the logical relationships between the major deliverables. business process reengineering. and how will they judge the project’s success. This task needs an understanding on the systems development organization structure. objectoriented development or integrated CASE. It is necessary that clear expectations for each personnel and how their job functions contribute in the overall goals and objectives of the project be communicated for smooth collaboration. what is a reasonable schedule range based on size. It is represented as a range of values. The figure below illustrates this structure
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. integration issues. potential revenue. who will judge the success of the project. It may be “make or buy” alternative or technical approach such as traditional coding.
Project Organization
The project organization integrates the functions of the personnel in a project. cost and benefit. productivity improvements. It includes potential savings. It answers the questions what are the major deliverables. It answers the questions how will we know when the project is completed. It answers the questions what are the costs associated with the effort required to produce each major deliverables. company or product positioning. It should meet the project objectives in the best way. and what operating costs need to be considered and identified. and other tangible and intangible benefits.Success Criteria It identifies the high-level deliverables that must be in place in order for the project to be completed. what assumptions were used to develop the schedule. improved quantity or quality. Costs It represents the estimated cost of developing the software. It provides specific measurement used to judge success. It should support the project objectives. Alternatives It defines the alternative solutions to the business problem or need. It should be analyzed based on likelihood of occurrence and impact. Each alternative should be evaluated to determine the schedule. effort. what other non-labor costs need to be considered. Risks It identifies risks of each alternative. dependencies and assumptions. and how the risks can be mitigated. what are the costs associated with hardware and software. Benefits It may be short or long term benefits. and risk. Recommendation The proposal team should work together to select best alternative that best balances project schedule.

CEO or Managing Director or Partner). It is a small group of with a leader or manager. Controlled Decentralized (CD) The Controlled Decentralized (CD) Team Structure has a permanent leader who primarily coordinates tasks. and quality assurance members. Comptroller). Consultants. user staff. and • releasing operational system to user. • approving and allocating resources for the project. • approving critical system change request. Democratic Decentralized (DD) The Democratic Decentralized (DD) Team Structure has no permanent leader. The communication is highly horizontal. The end-user group consists of EDP or MIS Staff. It requires team spirit. analysts.
The Project Team Structure
The team structure can be organized as democratic decentralized. controlled decentralized and controlled centralized. developers and end-user.Steering Committee The Steering Committee defines some business issues that have a great effect on the development of the project. • synchronizing the system development effort with the rest of the organization’s activities. casuals and consultants. • resolving conflict situations. • regularly assessing progress of the project. Decisions are solved by group consensus. Rather. there are task coordinators appointed for a short duration who are replaced later on by others who may need to coordinate other task. MIS or EDP Management and optionally. contribution and coordination. Their functions consists of: • formalizing the project team composition. Developers consist of the project manager. It is composed of top management (the President. Project Team The project team is composed of two sets of groups. programmers. Line Management (Functional Vicepresidents or Division Heads). They regularly interact to fulfill a goal. namely. Staff Management (Corporate Planning. designers. • reviewing and approving project plans and recommendations. It has a secondary leader responsible 95
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The communication during implementation is horizontal but control is vertical. It avoids problems encountered with communication and obligations from being neglected.
Project Responsibility Chart
The Project Responsibility Chart is a matrix consisting of columns of individual or functional departments. It supports the need to communicate expectations and responsibilities among the personnel involved in the development of the software. It answers the following questions: • Who is to do what? • How long will it take? • Who is to inform whom of what? • Whose approval is needed for what? • Who is responsible for which results? • What personnel interfaces are required? • What support is needed form whom and when?
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.for subtasks. Decisions are solved by group consensus but the implementation is done by subgroups. Use the table below to determine the team structure to be used for a project. The communication between leader and team members is vertical. Controlled Centralized (CC) The Controlled Centralized (CC) Team Structure has a team leader responsible for team coordination and top-level decision-making. The decision on what team structure to employ would depend on the project characteristics. and rows of required actions.

It is iterative process and must be flexible to accommodate changes. time constraints. portrays the interactions among these pieces of work and estimates the time that each task or activity will take. The product and process are decomposed into manageable activities and tasks. Each task must have a start and end date subject to interdependency and people responsible for the task (part-time or fulltime). Some of them are enumerated below. breaks each into discrete tasks or activities to be done. 3. Tasks can occur in sequence or parallel. It enumerates phases or stages of the projects. Each task should be allocated some number of work unit (persondays or man-days of effort). Compartmentalization. 1. Tasks can occur independently. Interdependency.
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. It is a team process that gives the start point of formulating a work program. 2.Project Scheduling
Project Scheduling is the task that describes the software development process for a particular project. and resource limitations to accomplish specific objectives. There are certain basic principles used in project scheduling. The interdependency of each compartmentalized activity or task must be determined. It is a time-phased sequencing of activities subject to precedence relationships. Time Allocation.

Project Work Breakdown Structure (WBS)
The Project Work Breakdown Structure (WBS) is a tool that allows project managers to define task sets. No more than the allocated number of people has been allocated at any given time. Project Scheduling identifies activities or task sets. Define Milestones. It should be executed until it finishes without any interruption. milestones and deliverables. A deliverable is a list of items that a customer expects to see during the development of the project. namely. Its duration and cost can be measured. It can include documents. Deliverables. 3. demonstrations of functions. Work products are combined in deliverables. Define the Work Unit or Package.
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. WBS Top-down Decomposition and Bottom-up Integration Process This method defines two major activities as specified in its name. Effort Validation. specifically. 2. • Analysis starts by identifying the major phases and the major deliverables that each produces. • Identify intermediate and final deliverables for each grouping. 2. milestones and deliverables. Define Responsibility. The work unit or package is the responsibility of one person. It is part of a project that takes place over a period of time. The tasks and milestones can be used in a project to track development or maintenance. 6. demonstrations of subsystems. 5. This atomic activity is called the work unit or package. Two methods are used in defining the work breakdown structure. Define Outcome.4. 3. milestones and deliverables that must be accomplished to complete a particular project. Examples of project milestones are user signoff. Do not worry about the sequence. • Continue to subdivide an activity until you get to an activity that cannot be subdivided anymore. Activities or Task Set. Arrange the blocks into a logical hierarchy. It is not duration of work. Each task or group of tasks should be associated with a project milestone. An activity or task set is a collection of software engineering work tasks. security or speed. Project milestones are reviewed for quality and approved by project sponsor. demonstrations of accuracy and demonstration of reliability. Milestones. Break the project into blocks of related activities. It should be a team member. 1. break them to define sub-activities and the work products produced by these sub-activities. and requires the continuous use of a resource group. Each task must have an owner. • For each activity. the topdown decomposition and bottom-up integration. Top-down Decomposition • Identify 4-7 major components of work. It references a particular moment of time. Each task must have a defined outcome. It signifies points of accomplishments within the project schedule. Work Breakdown Analysis The Work Breakdown Analysis consists of the following steps: 1. It is a systematic analysis approach of depicting a project as a set of discrete pieces of work. A milestone is an indication that something has been completed. the Work Breakdown Analysis and WBS Top-down Decomposition and Bottom-up Integration. 7. approved system design. It is written as a verb-noun phrase. 1. and system turnover.

graphical or hierarchy chart and outline format. Recommended number of levels is four(4). Graphical or Hierarchy Chart An example of a hierarchy chart of Pre-joint Meeting Task of Requirements Engineering is shown in the figure below. It is a chart that consists of bars that indicates the length of the tasks. 2. The horizontal dimension indicates the time while the vertical dimension indicates the task. Bottom-up Integration • Brainstorm all possible tasks.
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. namely.• Perform functional decomposition until a task has one owner. • Organize task into 4-7 major groupings reflecting how the project will be managed. credible estimates and can be tracked. • Multiple iterations are required.
Work Breakdown Schedule Format
There are two common formats that can be used to represent the WBS.
GANTT Chart It is an easy way of scheduling tasks. clear deliverables. Table 35 shows an example of a GANTT Chart. • Use verb-object at lowest task level.

The Resource Availability Database specifies what resources are required against the resources that are available. The table below shows an example. They are needed in order to achieve software goals and objectives. skills etc to the tasks identified in the project. information. equipment. people. They are: • Time Constraints • Resource Constraints • Performance Constraints
Resource Availability Data Base
The project manager must use the resource availability database to manage resources allocated for each task set. tools. facilities.
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.Project Resource Allocation
The project resource allocation is the process of allocating or assigning money. There are three major project constraints that are always considered in a software development project.

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Measurements can be applied to the software process with the intent of continuing the improvement of the process. It is important that the metrics of other projects are placed within a table to serve as reference during estimation. Direct Measures. maintainability etc. memory size and defects reported over a period of time 2. It allows software engineers to make decisions on how to progress within the development effort. productivity assessment and project control. It refers to the measure on the output of software process. reliability. It is used to collect direct measures of software output and quality based on the program’s functionality or utility. quality control.
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. Technical Metrics. 4. Human-Oriented Metrics. Size-Oriented Metrics. 2. quality. It is used to collect direct measures of software output and quality based on the line of codes (LOC) produced. complexity. it can be the lines of codes (LOC) produced. It is also known as the software’s fitness for use. 6. 1.Software Metrics
Software Metrics refers to a variety of measure used in computer software. Examples of metrics that are applied to software projects are briefly enumerated below. The table below shows an example of this. In software process. It provides measures collected about the manner in which people develop computer software and human perception about the effectiveness of tools and methods. It can be used by software engineers to help assess the quality of work products and to assist in the tactical decision-making as project proceeds. execution speed. It can be product measures such as functionality. Each chapter provides the metrics that are normally used to help software engineers the quality of the software and the process. number of classes. degree of collaboration and modularity etc. Indirect Measures. Function-Oriented Metrics. 3. It can be used throughout a software project to assist in estimation. project or the software product.Lines of Codes (LOC)
A common direct measure used for software metrics is the Lines of Code (LOC). Software Metrics are used as indicators to provide insight into the software process. Productivity Metrics. efficiency. Different phases or activities of the development projects required different metrics.
Size-oriented Metrics. Quality Metrics. In software. it can be the cost and effort applied. Categories of Measurement There are roughly two categories of measurements: 1. 5. It refers to the measure on the characteristics of the product such as complexity. It refers to the measure that provides indication of how closely software conforms to the requirements. It is a size-oriented metrics used to estimate effort and cost.

e. and people is the number of people who developed the software. One can derive metrics from this table. Computing the Function Point STEP 1. i. Example computations are shown below. if the number of input is 3 and the input data are simple. errors is the number of errors reported after the software was delivered to the customer. Productivity = KLOC / person-month Quality = errors / KLOC Cost = Cost / KLOC Documentation = Pages / KLOC
Function-Oriented Metrics: Function Points (FP)
Another metric that is commonly used is the Function Point (FP) Metrics. pages is the number of pages of documentation. KLOC is the lines of codes produced. It focuses on the program functionality or utility. Fill-up the count column and multiply the value with the chosen weight factor. 3 x 3 = 9. effort in person-month specifies the number of months the project was developed. Determine the value of the information domain by using the table shown in the table below .In this table. As an example. It uses an empirical relationship based on countable measures of software’s information domain and assessments of software complexity. cost is the money spent producing the software..
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. chose the weight factor of 3.

Are the master files updated on-line? 9. Are the inputs. Are data communications required? 3. heavily utilized operational environment? 6.65 + 0. Is performance critical? 5. Does the system require reliable backup and recovery? 2. Are there distributed processing functions? 4. or inquiries complex? 10. files. Will the system run in an existing. Are conversion and installation included in the design? 13. Productivity = FP / person-month Quality = Defects / FP Cost = Cost / FP Documentation = Pages of Documentation / FP
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. Is the application designed to facilitate change and ease of use by the user? STEP 3. Use the formula indicated below. Does the on-line data entry require the input transaction to be built over multiple screens or operations? 8. Is the code designed to be reusable 12. Examples of that are listed below. Is the internal processing complex? 11. outputs.1.01 x sum (Fi)] One can also derive metrics similar to size-oriented metrics. Compute for the function point. FuntionPoint = Count-Total X [0. Is the system designed for multiple installations in different organizations? 14. Does the system require on-line data entry? 7.

and commitment to quantitative measures when qualitative data are all that exists. To do estimation. we computer first the FP. As an example. access to good historical data.Project Estimations
Project estimations are necessary to help software engineers determine the effort and cost required in building the software. it would require experience. They provide estimate variables to “size” each element of the software. consider the project estimates for the club membership maintenance system. To use LOC and FP to determine the cost and effort estimate.
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. They provide a baseline metrics collected from past projects and used in conjunction with estimation variables to develop cost and effort projections. One can use LOC and LP to provide cost and effort estimates.

FP = 59 X [0.01 x 31] = 56.64 Effort Estimates are computed as follows: Number of LOC produced in a month (From the Database): KLOC/Effort KLOC/Effort = 15.00 = P7136. A risk is considered a potential problem.9 or 2 months
Risk Management
Risk Management consists of steps that help the software engineers to understand and manage uncertainty within the software development process. it may happen or it may not.65 + 0.000/15. estimate its impact and establish a contingency plan if it does 106
.00/LOC Cost of the project = 3568. Cost Estimates are computed as follows: Cost of Producing a single LOC (From the Database): KLOC / Cost Cost/KLOC = P30. The estimated LOC is computed as follows: LOC = 56.e. i.32 * 2. assess its probability of occurring.000LOC / 8 months = 1875 LOC / month Effort of the project = 3568. It is better to identity it.64 * 63 = 3568.32 / 1875 = 1..32 LOC Derived Estimates: Assume that the Club Membership Maintenance is similar to Project Four.000LOC = P2.64 FP The project heavily uses JAVA.

Technical Risks. component problems.
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. It is for this reason that understanding risks and having measures that avoid them influences how well the project is managed. Predictable Risks. 2. Project Risks. the software will become a problem in a business setting. These are risks associated with the implementation aspects of the software. If a risk becomes a reality. building a software that cannot be market and losing budgetary and personnel commitment. If such risk becomes a reality. Known Risks. This may include building a software that no one needs. Many things can happen during the progress of the development of the software. They should be considered as potential problems may arise from them. These are risks that are not detected. budgetary and resource problems. business environment analysis. There are different categories of risks that the software engineer needs to understand. This may include design and interface problems. 1. If such risk becomes a reality. These are risks that came from past similar projects that are expected to happen with the current one. it would be very difficult for us to implement the project. database and infrastructure problems. These are risks associated with the project plan. Business Risks. These are risks that can be detected with careful evaluation of the project plan. and understanding them also allows the creation of contingency plan with minimal impact to the software development project. and other good informational sources. The level of uncertainty and degree of loss associated for each risk are identified and documented.happen. bad consequences and losses will occur. 4. chances are there would be delays. Risk always involved uncertainty. 6. These are risks associated with the viability of the software. This means that risks may or may not happen. 3. If such risk becomes a reality. 5. Unpredictable Risks. Two important characteristics of risk are always analyzed and identified in risk management.

It would result in inconvenience or usage problems. These are risks that are related to the software process and how the people involved in the development effort are organized. 2. Staff Size and Experience. The last column contains the RMMM (Risk Mitigation.Marginal. It would result in failure to meet the requirements would result in degration of secondary mission. It is a brief description of the risk. 1. Development Environment. It defines the condition by which the risk may be realized. Risk Mitigation and Monitoring. It would result in failure to meet the requirements and non acceptance of the software. As software engineers. 4. 1. Process Definition. 4. Monitoring and Management) plan for each risk. and they are briefly enumerated below. Categorization identifies the type of risks. the impact of the risk when it occurs is identified.Catastrophic. These are risks that are related to the complexity of the system and the degree of newness that is part of the software. These are risks that are related to the constraints imposed by management or market. 4. Product Size Risks The product size is directly proportional to the project risk.First column lists down all possible risk including those that are most likely not to happen. It is a unique identification number that is assigned to the risk. These are risk that are related to the overall technical and project experience of the software engineers. we take a look at the following: • How large is the estimated size of the software in terms of lines-ofcode and function points? • How many is number of programs. Risk Context. It is assessed using the following values. It defines the steps that need to be done when the risk is realized. Description. Customer Characteristics. It contains the following components: 1. files and transactions? • What is the database size? • How many is the estimated number of users? • How many components are reused? 108
. Each risk are then categorized.Negligible.Critical. 7.
Risk Identification Checklist
One can use the following to determine risks within the software development project. 2. It defines the steps that need to be done in order to mitigate and monitor the risk. 2. These are risks that are related to the availability and quality of the tools that are used to develop the software. 3. 3. 5. 5. Next. 6. These are risks that are related to the overall size of the software that needs to be developed. Contingency Plan. These are risks that are related to end-user’s requirements and the ability of the development team to understand and communicate with them. It would result in failure to meet the requirements with system performance degration to the point of mission success is questionable. 3. Product Size. The probability value of the risk is identified as a percentage value of it occurring. Risk ID. Technology. Business Impact.

Business Impact Risks • What is the business value of the software to the company or organization? • What is the visibility of the software to senior management? • How reasonable is the delivery date? • How many is the customers? • How many are the products or systems that interoperate with the software? • How large is the project documentation? • Does the product documentation have quality? • What are the governmental constraints applied to the development of the project? • What is the cost associated with late delivery? • What is the Cost associated with a defective product? Customer Related Risks • What is the customer working relationship? • What is the level of the customer’s ability to state their requirements? • Are customers willing to spend time for requirements gathering? • Are customers willing to participate in formal technical reviews? • How knowledgeable are the customers in terms of the technological aspects of the software? • Do customer understand of the software development process and their role? Process Risks-Process Issues • Does senior management show full support or commitment to the software development effort? • Do the organization have a developed and written description of the software process to be used on this project? • Do the staff members know the software development process? • Is the software process used before in other projects with the same group of people? • Has your organization developed or acquired a series of software engineering training courses for managers and technical staff? • Are there any published software engineering standards that will be used by software developer and software manager? • Are there any developed document outlines and examples of deliverables? • Are formal technical reviews of the requirements specification. test cases done regularly? Do they have defined procedures? • Are the results of each formal technical review documented. design. and software development plan for each subcontract? Process Risks-Technical Issues • Are there any mechanism that facilitates clear communication between customer and developer? • Are there any specific methods used for software analysis? 109
. code. and test cases? • Do they have documents for the statement of work. design and code done regularly? Do they have defined procedures? • Are formal technical reviews of test procedures. including errors found and resources used? Do they have defined procedures? • Do they have procedures that ensure that work conducted on a project conforms to software engineering standards? • Do they use configuration management to maintain consistency among system/software requirements. software requirements specification.

1. It focused on managing change within the software development process. and artificial neural networks? Development Environment Risks • Are there any software project management tools employed? • Are there any tools for analysis and design? • Are there any testing tools? • Are there any software configuration management tools? • Are all software tools integrated with one another? • Do we need to train the members of the development team to use the tools? tools? • Are there any on-line help and support groups? Risk Associated with Staff Size and Experience • Is the staff turnover high? • Do we have skilled team members? • Is there enough number of people in the development team? • Will the people be required to work overtime? • Will there any problems with the communications?
7. or testing methods? • Do we need to use unconventional software development methods. AI-based approaches.• Are there any specific methods used for component design? • Are there any specific method for data and architectural design? • Are codes written in a high level language? How much is the percentage? • Are documentation and coding standards followed? • Are there any specific methods for test case design? • Are software tools used to support planning and tracking activities? • Are configuration management software tools used to control and track change activity throughout the software process? • Are CASE tools used? • Are quality metrics collected for all software projects? • Are there any productivity metrics collected for previous software projects? Technology Risks • Is the organization new to the technology? • Do we need to create new algorithms. The possible work products that can serve as software configuration items or units are listed below. input or output technology? • Do the software need to use new or unsupported hardware? • Do the software need to use a database system not tested in the application area? • Do we need to define a specialized user interface? • Do we need to use new analysis.Project Planning Phase 110
. controlling change. They are characterized based on the software engineering phase or activities they are produced. design. ensuring that change is being properly implemented. It consists of identifying change. It can occur any time as work products are developed and maintained. It manages items called software configuration items (SCIs) or units. documents (both technical or user) and data. and reporting the change to others who may be affected by it. which may be computer programs (both source-level and executable forms). such as formal methods.10 Software Configuration Management
Software Configuration Management is an umbrella activity that supports the software throughout its life cycle.

4 shows the dynamics of managing the baseline of SCIs.a)Software Project Plan 2.Standards and Procedures for Software Engineering
Baseline
Managing SCIs uses the concept of baseline. Implementation a)Source Code Listing b)Executable or Binary Code c)Linked Modules 5. A baseline is a software configuration management concept that helps software engineers control change without seriously impeding justifiable change. Once the work product passes or is acceptable.Design Engineering a)Database Design b)Dialogue and Screen Design c)Report Design d)Forms Design e)Software Architecture f) Component Design g)Deployment Design 4.
A Software Engineering Task develops a work product that becomes a software configuration item or unit.Testing a)Test Specifications b)Test Cases 6. It is a specification or product that has been formally reviewed and agreed upon to be the basis for further development. It can only be changed through a formal change procedure.Requirements Engineering a)System Specifications b)Requirements Model c)Analysis Model d)Screen Prototypes 3.Manuals a)User Manuals b)Technical Manuals c)Installation and Procedures for Software Engineering 7. It goes through a formal technical review to detect faults and errors. it becomes a baseline and 111
. Figure 7.

the constraints. It has the following subset of task: • A change request is submitted and evaluated to assess technical merit. Sometimes. checked in after the review and subject to version control. Change Identification It is the process of identifying items that change throughout the software development process.
Software Configuration Tasks
Software configuration management has the responsibility to control change. • The SCIs is checked out for modification. If it passed or acceptable. • A change report is created to identify the final decision on the status and priority of the change. In this case. version control. then. It specifically identifes software configuration items (SCIs) and uniquely gives it an identifier and name. It also audits the software configuration items to ensure that they have been properly developed and that the reporting of changes is applied to the configuration. It answers the following questions: • Was the change specified in the ECO done? Are there any additional modification made? • Did the formal technical review assessed the technical correctness of the work product? • Did the software engineering procedures been followed? • Did the SCM procedures been followed? • Have all appropriate SCIs been updated? Status Reporting It is the process of informing people that are affected by the change. change control. Change Control It consists of human procedures and automated tools to provide a mechanism for the control of change. During the execution of the SE task. Version Control It is the procedures and tools to manage the different version of configuration objects that are created during the software development process. Configuration Audit It is the process of assessing a SCIs for characteristics that are generally not considered during a formal technical review. A version is a collection of SCIs that can be used almost independently. this work product is extracted from the project database as input to some other software engineering task. It identifies software configuration items and various version of the software. Notices that "checking out" a SCI involves controls and procedure. configuration audition and reporting. change identification. • The Engineering Change Order (ECO) is created that describes the change to be make. the modified version becomes the new baseline. namely. and the criteria for review and audit. overall impact on other SCIs. Five tasks are done. • It is. it is possible that the SCI has been modified. the modified SCI will pass through another formal technical review. potential side effects. It answers the following questions: • What happened? • Who did it? 112
.is saved in a project database.

This type of tool supports the Software Configuration Management process. In Java. NetBeans is an example of an IDE. etc. a separate client and server 113
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Visual Editors
Creating graphical user interfaces can be difficult when done manually.
Database Management Tools
A considerable amount of software is needed for a large-scale database management system. attributes. C++ and SQL codes. Interpreters and Run-time Support
All source code must be translated into an executable code. Visual Basic. can perform some testing and debugging. state. Rational Rose. Visual Editors allows the creation of these interface by simply dragging and dropping the components onto the forms and setting the parameters that control their appearance in a properties window. links to the compiler so that codes can be compiled from within the IDE. This environment is supported by most browsers. and a debugger to help the programmer step through the code to fine errors. software development tools are presented.
Integrated Development Environment (IDE)
Integrated Development Environment (IDE) incorporates a multi-window editor.
Configuration Management
Configuration Management Tools are tools the support the tracking of changes and dependencies between components and versions of source codes and resource files that are used to produce a particular release of a software package. There are tools that generate Java. If support for client-server mode of operation is needed. to the diagrammatic representation. operation. the source code is compiled into a intermediary bytecode format that is interpreted by the Java Virtual Machine (JVM). The main feature of such software is the project repository which allows the maintenance of the links among the textual and structured descriptions of every class. NetBeans supports this kind of visual editing. it means that you can run java programs using simply a browser. In this chapter. This type of software development tools enable a software engineer to manage source codes in a single interface. There are now several tools that support the Unified Modeling Language (UML). This ensures that the implementation reflects the design diagrams.
Compilers. umlet. Example of this tool is Concurrent Version System(CVS). Some IDEs have visual editors.• When did it happen? • What else will be affected?
Chapter 7 Software Development Tools
The implementation of software requires a variety of software tools. mechanisms for managing files that make up the projects. Examples of CASE Tools are ArgoUML. Many of these tools have been designed and implemented to make the work of the software engineer easier and organized. and Dia. Other CASE Tools supports code generators.
Case Tools
Computer-aided Software Engineering (CASE) tools are software that allows the software analysts create models of the system and software. Ensuring that these are available in compatible versions and with sufficient licences is part of project management. and at the same time.

Packages like Data Junction provide automated tools to extract data from a wide range of systems and format it for a new system.
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Installation Tools
This tools allows the creation of installation executable files that when run automates the creations of directories.components should be installed.
Software Project Management
Software Project Management tools supports project management. MS Project is an example of this tool. Such as when ODBC or JDBC is used. Java has javadoc that processes Java source files and generates HTML documentation in the style of the API documentation from special comments with embedded tags in the source code. ObjectStore PSE Pro includes a post-processor that is used to process Java class files to make them persistent. What is more likely is that programmers will develop their own tools to provide harnesses within which to test classes and subsystems. It allows the project manager to set the project schedule. Nowadays.
Conversion Tools
This is type of tool is needed when an existing system needs to transfer its data to another system.
Testing Tools
These are tools that identifies test methods and generates test cases. extraction of files from the archives and the setting up of parameters or registry entries. manage resource such as time and people. track progress. additional special libraries or Java packages (specific DriverManager of a vendor)should be installed or available during run-time. new software replaces existing computerized system. Automated testing tools are available for some environment such as NetBeans' support for JUnit.
Document Generator
These are tools that allow the generation of technical or user documentation.